Dissertations / Theses: 'Luminiscencia'

1

Cabeza, Martínez José Francisco. "Preparación de materiales electroluminiscentes basados en compuestos adsorbidos en el interior de sólidos porosos." Doctoral thesis, Universitat Politècnica de València, 2008. http://hdl.handle.net/10251/3541.

Full text

Abstract:

La electroluminiscencia es el fenómeno por el cual ciertos materiales emiten luz visible cuando se someten a un potencial eléctrico. En este contexto, en la presente tesis doctoral se desarrollaron dispositivos electroluminiscentes tipo OLED basados en sistemas supramoleculares huésped/hospedador, donde el grupo luminóforo se encontraba incorporado en el interior de los microporos de zeolitas, estabilizando este grupo frente a procesos químicos y agentes ambientales que originan su degradación. Previamente, se prepararon una serie de películas de zeolitas, midiendo la conductividad eléctrica de cada una de ellas a diferentes voltajes de corriente directa. Tras esto, fue objeto de estudio la eficiencia electroluminiscente de los compuestos rutenio tris-bipiridilo y polifenilenvinileno encapsulados en el interior de zeolitas de poro grande tipo faujasita. Por otra parte, se ha llevado a cabo la incorporación de compuestos luminóforos en matrices rígidas inorgánicas (PMO) con el fin de aumentar su estabilidad y procesabilidad. Por último, se ha descrito la introducción covalente de grupos imidazolio en la estructura de un compuesto luminóforo. De esta manera, se favoreció el transporte de carga desde los electrodos externos hacia la capa activa, mejorando considerablemente la eficiencia de estas celdas electroluminiscentes. Los resultados obtenidos en la presente tesis doctoral describen una aplicación novedosa de los sistemas supramoleculares en la obtención de materiales electroluminiscentes, facilitando la preparación de nuevos y mejorados dispositivos OLEDs.
Cabeza Martínez, JF. (2008). Preparación de materiales electroluminiscentes basados en compuestos adsorbidos en el interior de sólidos porosos [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/3541
Palancia

APA, Harvard, Vancouver, ISO, and other styles

2

Montañez, Huamán Liz Margarita. "Synthesis and characterization of wide bandgap semiconductors doped with terbium for electroluminescent devices." Master's thesis, Pontificia Universidad Católica del Perú, 2016. http://tesis.pucp.edu.pe/repositorio/handle/123456789/6999.

Full text

Abstract:

In this work, stoichiometric, structural and light emission properties of amorphous wide bandgap semiconductor materials doped with terbium are presented. The amorphous nature of the thin films was confirmed by X-ray diffraction under grazing incidence. Fourier transform infrared spectroscopy spectra exhibit the formation of oxygen bonded elements and X-ray photoelectron spectroscopy reveals the formation of aluminum oxynitride and silicon oxycarbide as host matrices. The thin films were annealed at temperatures ranging from 300 °C to 1000 °C using a rapid thermal processing furnace. The highest light emission intensity for the case of aluminum oxynitride was obtained for terbium concentrations higher than 1 at% and for the annealing temperature at around 400 °C. Additionally, using the characterized films as active layer first electroluminescence devices were designed and investigated.
En el presente trabajo de investigación se ha estudiado propiedades estequiometrias, estructurales y de emisión de luz de semiconductor de amplio ancho de banda dopados con terbio. La difracción de rayos-X en ángulo rasante confirma el estado amorfo de las películas. Los espectros de absorción infrarroja muestran la formación de óxidos en las películas y la espectroscopia de foto-electrones de rayos-X revela la formación de oxinitruro de aluminio y oxicarburo de silicio. Las películas han sido calentadas a temperaturas en el rango de 300 °C a 1000 °C en un horno de rápido procesamiento térmico. De acuerdo con el análisis de las medidas de fotoluminiscencia, la intensidad más alta de emisión de luz del terbio es para películas que tengan concentraciones de terbio mayores al 1at% y a una temperatura de tratamiento térmico de alrededor de 400 °C. Adicionalmente, las películas analizadas han sido usado como capas activas para el diseño de dispositivos electroluminiscentes
Tesis

APA, Harvard, Vancouver, ISO, and other styles

3

Serquen, Infante Erick Stalin. "Efectos de la difusión sobre la luminiscencia de iones de terbio en una matriz basada en silicio durante el proceso de activación térmica." Master's thesis, Pontificia Universidad Católica del Perú, 2019. http://hdl.handle.net/20.500.12404/14324.

Full text

Abstract:

Los semiconductores dopados con tierras raras presentan gran interés de estudio científico debido a sus prometedoras aplicaciones en dispositivos optoelectrónicos, donde ya han encontrado múltiples aplicaciones como dispositivos de conversión ascendente y descendente de luz óptico, láser de uso médicos, pantallas luminiscentes, entre otros. El carburo de silicio posee un ancho de banda de 2;2 eV - 3;3 eV, es térmicamente estable ya que sublima a 2830 fC. Diversas investigaciones sobre carburo de silicio lo reportan como un buen material matriz para ser dopado con tierras raras. Por otro lado, las tierras raras a excepción de lantano y lutecio poseen incompletos los orbitales f que por ser internos no participan de enlaces y sólo se ven afectados por el entorno iónico, teniendo la capacidad de ser excitados cuando se encuentran embebidos en una matriz apropiada. Una característica fundamental de los materiales dopados con tierras raras es la emisión de luz que se ve mejorada cuando el material dopado es sometido a tratamientos térmicos en un rango de temperatura de 400 fC a 1000 fC, logrando así la activación térmica de los iones Tb3+, se cree que ésta mejora se debe a la interacción entre iones de Tb3+, donde la distancia interiónica juega un papel clave; además, del entorno cristalino de los iones y las simetrías (Regla de selección de Laporte). Con el propósito de investigar como el comportamiento difusivo de los iones de Tb3+ en la matriz de a-SiC tiene efecto en luminiscencia y a fn de establecer relaciones entre las energías de activación para la luminiscencia y la difusión, en este trabajo se presenta el estudio de estructuras bicapa depositadas por la técnica de pulverización catódica de radiofrecuencia con magnetrones sobre sustrato de silicio oxidados térmicamente. Las cuales fueron sometidas a diferentes tratamientos térmicos a temperaturas en un rango de 973 K-1273 K con tiempos entre 5 y 20 minutos. Después de cada tratamiento térmico las muestras fueron caracterizadas por refectividad de rayos X (XRR), catodoluminiscencia (CL) y espectroscopía de rayos X de energía dispersiva (EDS). La luminiscencia de las muestras, estudiadas con CL, presenta cambios al variar el voltaje de aceleración de electrones (fuente de excitación), a partir de este experimento se obtiene la energía de activación para la luminiscencia. La difusión de terbio se investigó mediante EDS, y los coeficientes de difusión se extrajeron de un ajuste de datos a funciones basadas en la solución de la segunda ley de difusión de Fick. Una simple aproximación a la ley de Arrhenius permite determinar la energía de activación para la difusión.
Tesis

APA, Harvard, Vancouver, ISO, and other styles

4

Tucto, Salinas Karem Yoli. "Structural, luminescence and Judd-Ofelt analysis to study the influence of post-annealing treatment on the AIN:Tb thin films prepared by radiofrequency magnetron sputtering." Master's thesis, Pontificia Universidad Católica del Perú, 2016. http://tesis.pucp.edu.pe/repositorio/handle/123456789/6998.

Full text

Abstract:

This thesis investigates the effects of the annealing treatments on the spontaneous emission, radiative lifetime, composition and structure of terbium doped aluminum nitride films deposited on silicon substrates by radio frequency magnetron sputtering. The purpose of this thesis is to determine the Judd-Ofelt intensity parameters from the emission spectrum, in order to calculate the radiative lifetime, branching ratios and spontaneous emission probability. The optimal annealing temperature for the emission of terbium doped aluminum nitride is investigated. The annealing treatment was performed in the temperature range starting from 500 up to 1000°C. Two annealing techniques were investigated: rapid thermal processing and a rather slower quartz tube furnace. Furthermore, two heating approaches were applied: direct heating at 500, 750, 900 and 1000 °C, and multistep heating of 500-750°C, 750-900°C and 900-1000°C. The film was then characterized to determine which conditions resulted in the highest emission of Tb. The film characterization includes the use of X-ray diffraction to study the film’s crystal orientation, Energy dispersive X-ray spectroscopy to determine the film composition, Scanning electron microscopy and Reflection high-energy electron diffraction to resolve the surface morphology and structure of the film respectively. The luminescent intensity and the radiative lifetime were analyzed using cathodoluminescence measurement and Judd-Ofelt analysis. This work shows that the activation of the Tb ions to enhance the emitted cathodoluminescence intensity depends on the structure of the film and the oxygen concentration. The best annealing temperature to produce the highest emitted light intensity in this set of experiments were the single-step heating at 750°C using rapid thermal processing.
En la presente tesis se investiga la influencia del tratamiento térmico en la probabilidad de emisión espontánea, el tiempo de vida radiativa, la composición y la estructura de películas delgadas de nitruro de aluminio dopadas con terbio depositadas sobre substratos de silicio por la técnica de pulverización catódica de radiofrecuencia. La tesis tiene por objetivo aplicar el análisis de Judd-Ofelt usando el espectro de emisión. Se propone un método que utiliza la intensidad de las bandas de transición del espectro de emisión y las ecuaciones de Judd-Ofelt para calcular las propiedades espectrales: tiempo de vida radiativa, tasa de los canales de transición y probabilidad de emisión espontánea. Usando el software Wolfram Mathematica 9.0 se implementa un programa con el método propuesto. Las películas se trataron térmicamente a 500, 750, 900 y 1000 °C. Se investigaron dos técnicas del tratamiento térmico: Tratamiento térmico rápido y Horno tubular de vidrio de cuarzo. Con el tratamiento térmico rápido se usaron dos tipos de calentamiento: calentamiento directo a la temperatura de tratamiento térmico, y calentamiento sucesivo de la película desde la menor hasta la mayor temperatura. El análisis estructural de las películas fue realizada con difracción de rayos X. A nivel de superficie se caracterizó la estructura y la morfología con las técnicas de difracción de electrones reflejados de alta energía y microscopía electrónica de barrido. La luminiscencia fue medida con la técnica de catodoluminiscencia. Las propiedades espectrales fueron calculadas usando el método propuesto. La intensidad de luz emitida se incrementó y luego decayó con la temperatura de tratamiento. La relación entre la intensidad de emisión, la estructura, composición y los parámetros de Judd-Ofelt son mostrados mediante gráficas y tablas. Los resultados obtenidos muestran una mayor activación de los iones de terbio en las películas calentadas directamente a 750°C usando el tratamiento térmico rápido.
Tesis

APA, Harvard, Vancouver, ISO, and other styles

5

Casanovas, Bayo Berta. "Compostos de coordinació magnètics i/o luminescents derivats d'elements 3d o 4f: Cercant sistemes multipropietat." Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/586178.

Full text

Abstract:

Amb l’objectiu d’obtenir materials moleculars amb una o més propietats físiques tals com magnètiques, luminescents i/o quirals en aquest treball s’han obtingut nous compostos de coordinació basats en metalls de transició, concretament amb manganès, o bé amb ions lantànid trivalents Ln(III). Les propietats físiques observades en aquests complexos deriven dels propis metalls, dels lligands orgànics coordinats a aquests o bé es deuen a la cooperativitat metall-lligands. Treballant amb ions manganès i lligands salicilaldoxima (H2-salox) i azidur s’ha obtingut el compost octanuclear (Pr4N)2[MnII2MnIII6(μ3-O)2(μ1,1- N3)6(salox)6Cl2(H2O)2]·(H2O). L’estudi magnètic revela un comportament ferromagnètic global amb estat d’espín fonamental màxim de S = 17 i resposta SMM. L’estat S fonamental observat és degut a que l’acoblament ferromagnètic entre els ions Mn(II) (amb entorn tetraèdric) i Mn(III) via el pont azidur amb mode de coordinació end-on és dominant respecte a les interaccions entre els ions Mn(III) dins dels triangles. Per altra banda, s’han presentat sis compostos obtinguts a partir de diferents lligands H2-R-salox (R= H per H2-salox; 3-CH3 per H2-3-Me-salox; CH3 per H2- Me-salox; CH2CH3 per H2-Et-salox) i anions 9-antracecarboxilat (9-AC) i que presenten la unitat triangular {Mn3O(R-salox)3}-. Quan s’ha treballat amb lligands H2-salox i H2-3-Me-salox, s’ha observat que la topologia del compost obtingut canvia en funció de si hi ha presència d’ions Na+ o Cs+ degut al diferent valor de radi iònic entre aquests dos cations alcalins. Aquesta dependència estructural no s’ha observat en emprar lligands H2-Me- salox i H2-Et-salox. L’estudi magnètic revela que en tots els compostos es compleix la correlació magneto-estructural que relaciona la torsió intramolecular Mn-N-O-Mn amb el bescanvi magnètic dins aquestes unitats. S’ha observat comportament d’imant molecular en els compostos derivats dels lligands H2-Me-salox i H2-Et-salox. En tots aquests compostos s’han observat propietats luminescents derivades de la presència del lligand 9-AC. En la segona línia de recerca presentada en aquest treball, s’han obtingut nous compostos de coordinació de Ln(III) amb presència dels àcids carboxílics 9- antracecarboxílic (H-9-AC), el 2-fluorobenzoic (H-2-FBz), els (R)/(S)-(±)-2-(6- metoxi-2-naftil)propiònic (R- o S-HL1) i els (R)/(S)-(±)-2-fenilpropiònic (R- o S- HL2) i lligands secundaris N-donadors 1,10-fenantrolina (phen), 2,2’-bipiridina (bpy) o 2,2’:6’,2’’-terpiridina (terpy). En aquests tipus de compostos s’ha buscat que les propietats luminescents derivin de la sensibilització de les transicions f-f dels ions Ln(III) per part dels diferents lligands orgànics coordinats a aquests. En alguns casos s’han observat diferents estructures sota una mateixa combinació de lligands a causa de la contracció del radi iònic dels lantànids. Entre els diferents compostos de coordinació obtinguts s’ha demostrat la coexistència de propietats magnètiques i luminescents per [Ln2(9-AC)6(bpy)2] (Ln(III) = Nd, Er i Yb), [Ln2(9-AC)6(phen)2] (Ln(III) = Er i Yb), [Ln(9- AC)3(terpy)(H2O)]·H2O·DMF (Ln(III) = Er i Yb), [Ln2(2-FBz)4(NO3)2(phen)2] (Ln(III) = Nd, Dy i Er), [Yb2(2-FBz)6(phen)2] i [Ln2(2-FBz)6(terpy)2]·H-2-FBz·H2O (Ln = Nd, Dy, Er i Yb). La presència de les espècies enantiomèricament pures dels àcids carboxílics quirals R- o S-HL1 o bé R- o S-HL2 ha derivat en la obtenció dels compostos amb comportament imant, luminescents i quirals [Ln2(R-L1)6(phen)2]·3DMF·H2O i [Ln2(S-L1)6(phen)2]·3DMF·H2O (Ln(III) = Nd i Dy), [Nd2(R-L2)6(phen)2]·2.5S-HL2 [Nd2(S-L2)6(phen)2]·2.5S-HL2, [Yb2(R-L2)4(NO3)2(phen)2]·2R-HL2 i [Yb2(R- L2)4(NO3)2(phen)2]·2R-HL2. A més, també a causa de la quiralitat dels compostos induïda pels lligands carboxilat, s’ha observat luminescència circularment polaritzada en estat sòlid en els compostos [Eu2(R-L1)6(phen)2]·3DMF·H2O, [Eu2(S-L1)6(phen)2]·3DMF·H2O i en [Ln2(R-L2)6(phen)2]·2.5S-HL2 [Ln2(S- L2)6(phen)2]·2.5S-HL2 (Ln(III) = Eu i Tb).
The aim of this work is to obtain molecular materials that display one or more physical properties such as magnetism, luminescence and/or chirality. Based on coordination chemistry, we have synthesised new compounds with transition metals or with lanthanide trivalent ions (Ln(III)). The physical properties observed in these compounds arise from the metals, from the ligands coordinated to them or from the metal-ligand cooperativity. We have isolated a MnII2MnIII6 compound using salicyladoxime (H2-salox) and azide (N3-) ligands. Magnetic study of this compound reveals a spin ground state of S = 17, the highest possible for this system. The stabilization of this maximum magnetic ground state is due to the dominance of the ferromagnetic exchange between the Mn(II) and Mn(III) through the N3- ligand. Continuing with manganese, a series of {Mn3O(R-salox)3}- based compounds have been obtained using H2-salox, H2-3-Me-salox, H2-Me-salox or H2-Et-salox ligands and the sodium or caesium 9-anthracenecarboxilate (9-AC) salt. A structural dependence is observed when using H2-salox or H2-3-Me-salox with Na+ or Cs+ carboxylate salt. The magnetic properties of the obtained compounds are strongly dependent on the R- group of the R-salox ligand. Luminescence properties have been observed in these compounds. On the other hand, several new Ln(III) coordination complexes have been obtained combining different carboxylic acids [H-9-AC, 2-fluorobenzoic acid (H- 2-FBz), R/S-2-(6-methoxy-2-naphthyl)propionic acid (R- o S-HL1) or R/S- phenylpropionic acid] with different N-donor secondary ligands (2,2’- bipyridine, 1,10’-phenanthroline or 2,2’:6’,2’’-terpyridine). Under these conditions, we have obtained compounds [Ln2(9-AC)6(bpy)2] (Ln(III) = Nd, Er and Yb), [Ln2(9-AC)6(phen)2] (Ln(III) = Er and Yb), [Ln(9- AC)3(terpy)(H2O)]·H2O·DMF (Ln(III) = Er and Yb), [Ln2(2-FBz)4(NO3)2(phen)2] (Ln(III) = Nd, Dy and Er), [Yb2(2-FBz)6(phen)2] and [Ln2(2-FBz)6(terpy)2]·H-2- FBz·H2O (Ln = Nd, Dy, Er and Yb) which display magnetic and luminescent properties. The use of pure enantiomeric species of R- o S-HL1 or R- o S-HL2 led to the isolation of magnetic, luminescence and chiral compounds [Ln2(R- L1)6(phen)2]·3DMF·H2O and [Ln2(S-L1)6(phen)2]·3DMF·H2O (Ln(III) = Nd and Dy), [Nd2(R-L2)6(phen)2]·2.5S-HL2, [Nd2(S-L2)6(phen)2]·2.5S-HL2 and [Yb2(R- L2)4(NO3)2(phen)2]·2R-HL2 and [Yb2(R-L2)4(NO3)2(phen)2]·2R-HL2. Moreover, chiral compounds [Eu2(R-L1)6(phen)2]·3DMF·H2O, [Eu2(S- L1)6(phen)2]·3DMF·H2O and [Ln2(R-L2)6(phen)2]·2.5S-HL2 [Ln2(S-L2)6(phen)2]·2.5S- HL2 (Ln(III) = Eu and Tb) display Circularly Polarized Luminescence.

APA, Harvard, Vancouver, ISO, and other styles

6

García, Bueno Rocío. "Estudio de las propiedades ópticas y magnéticas de complejos pentacoordinados de níquel(II)." Doctoral thesis, Universidad de Murcia, 2012. http://hdl.handle.net/10803/84062.

Full text

Abstract:

Síntesis, caracterización y estudio de las propiedades luminiscentes y magnéticas de complejos pentacoordinados de níquel(II) con ligandos orgánicos del tipo: 8-hidroxiquinolinas, imidas, benzazoles y ácidos mono- y dicarboxílicos. Utilización de estos complejos como sensores luminiscentes en la detección de cationes metálicos de interés biológico y/o ambiental.

APA, Harvard, Vancouver, ISO, and other styles

7

Arredondo, Amigo Juan Francisco. "Estimación de la radiación ionizante ambiental de fondo mediante el uso de dosímetros de luminiscencia ópticamente estimulada y análisis espacial : estudio de caso de la Región Metropolitana." Tesis, Universidad de Chile, 2017. http://repositorio.uchile.cl/handle/2250/150996.

Full text

Abstract:

Memoria para optar al Título Profesional de Ingeniería en Recursos Naturales Renovables
El presente trabajo es presentado como un aporte al estudio de la radiación ionizante en Chile y en particular busca colaborar en la discusión del tema de la radiación ionizante ambiental (RIA), el cual ha sido un área de investigación poco explorada a nivel nacional. Para lo anterior se analizó la Región Metropolitana de Santiago como una experiencia de aprendizaje que permitió dar respuesta a la siguiente interrogante: ¿Cómo varía la radiación ambiental en las diferentes zonas de la Región Metropolitana de Santiago?. Ésta pregunta surge de la necesidad de conocer cómo afecta la radiación ambiental al monitorear las dosis de los trabajadores que se ven expuestos a radiación ionizante en sus puestos de trabajo. El estudio consistió en tres fases, primero, confirmar la factibilidad de utilizar dosímetros OSLInLight® de Luminiscencia Opticamente Estimulada con el fin de monitorear RIA y utilizarlos para determinar una expresión matemática que relacione la dosis de RIA en función del tiempo. Para esto, se realizó una recta de regresión a partir de los datos de dosis de fondo mensuales almacenados en dosímetros OSL InLight® de los últimos 4 años en la Región Metropolitana determinando una dosis de 0,66 mSv anual. Mediante el uso de la recta de regresión y puntualmente para el año 2014-2015 se registró una dosis promedio de 0,68 mSv con una desviación estándar de 0,03.

APA, Harvard, Vancouver, ISO, and other styles

8

Albert, García Jose Ramón. "Desarrollo de la estrategia analítica multiconmutación-fotodegradación-luminiscencia para la automatización en el control de pesticidas. Aplicación de la conectividad molecular para la predicción de los procesos estructurales." Doctoral thesis, Universitat de València, 2008. http://hdl.handle.net/10803/10259.

Full text

Abstract:

A high-priority line research in Analytical Chemistry is the development of methods and techniques that increase the automatization degree and, therefore, reduce the human participation in the analysis procedures. The demand of information makes necessary the development of simple, cheap, fast and clean methodologies. This Doctoral Thesis was devoted to develop new and automated systems for pesticide analysis on samples of environmental interest. To achive this goal we studied an analytical strategy based on Multicommutation, luminescence (chemiluminescence and fluorescence) and photodegradation. To implement the analytical objectives we also applied the Molecular Connectivity to predict the luminescent behaviour of organic molecules. This Doctoral Thesis combines a new, cost-effective and sensitive analytical strategy for the determination of pesticides based on:- Multicommutation, an automatic methodology by using solenoid valves device,- Luminescence as high sensitive detection technique and,- Photodegradation as a simple derivative mean of analytes, And a way to predict the luminescent properties of organic molecules by using the Molecular Connectivity. All together would be useful in the future help in the search and selection of new structures with theoretical luminescent or others interesting properties.

APA, Harvard, Vancouver, ISO, and other styles

9

Blasi, Davide. "Molecular and supramolecular strategies for highly luminescent trityl radicals and their sensing applications." Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/405307.

Full text

Abstract:

Dentro del campo de la óptica y de la optoelectrónica, los radicales orgánicos se están convirtiendo en prometedores materiales gracias a su configuración de capa abierta. En este marco, el objetivo de esta tesis ha sido el desarrollo de radicales tritilo fotoestables y altamente luminiscentes. En el capítulo I, tras una introducción sobre la luminiscencia, se describirán las propiedades ópticas de los radicales libres de carbono central, centrándose en las capacidades y perspectivas que ofrecen estas moléculas en la microscopía de fluorescencia y en dispositivos electroluminiscentes. En el capítulo II, se presentarán las propiedades ópticas de los radicales tris(2,4,6-triclorofenil)metilo (TTM) y perclorotrifenilmetilo (PTM) cuando se emplean como especies emisoras en nanopartículas orgánicas (ONPs) y en películas poliméricas. Además, a pesar de que existe un amplio conocimiento sobre las propiedades luminiscentes de estos radicales en solución, no hay estudios acerca del efecto del confinamiento de estos radicales en matrices rígidas orgánicas. Como sistemas huéspedes, se han escogido el tris(2,4,6 triclorofenil)metano (TTM-αH) y el poli(metilmetacrilato) para nanopartículas orgánicas y películas, respectivamente. De especial interés resulta el caso del TTM dopado con nanopartículas orgánicas (TTMd-ONPs) en el que se observa, por primera vez, la formación de excímeros en radicales libres de carbono central. Ambos sistemas resultan de gran interés ya que, por primera vez, se observan emisiones de excímeros desde radicales libres de carbono central debido a la formación de pares de radicales supramoleculares estables y persistentes. Gracias a su emisión en la zona NIR-roja (650-800 nm), estos materiales basados en excímeros de radicales libres se han convertido en materiales moleculares muy prometedores para la bioimagen y en aplicaciones optoelectrónicas. En el capítulo III, se estudiarán los procesos de asociación y disociación de los excímeros de TTM (estructura molecular, naturaleza del receptor, efectos térmicos). En particular, se ha encontrado que el TTMd-ONPs ofrece la posibilidad de ser utilizado como nanotermómetro rentable y radiométrico. En este marco, se ha estudiado la salida ratiométrica de la suspensión acuosa de TTMd-ONPs al 20% en diferentes condiciones de polaridad, fuerza iónica y pHs, con el objetivo de probar su posible aplicación como biosensor térmico. Finalmente, en el capítulo IV, se presentará la síntesis del primero ejemplo de polibromotrifenilmetil radical. Esta nuevo radical constituye un componente prometedor para la síntesis de radicales tritilo altamente luminiscentes y fotoestables. De hecho, gracias a la triple funcionalización de bromo en las posiciones para, este nuevo radical permite fácilmente superar la poca versatilidad sintética de los radicales policlorotrifenilmetilo. Además, en comparación con su especie análoga clorada, el radical tris (2,4,6 tribromofenil)metilo (TTBrM) presenta una absorción y emisión desplazados hacia el rojo , alta fotoestabilidad, y es capaz de formar excímeros NIR cuando se dispersa en nanopartículas orgánicas, transformándose en un radical muy prometedor para aplicaciones en bioimagen.
Organic radicals are emerging as promising materials in optics and optoelectronics thanks to their open-shell configuration. In this framework, the aim of this Thesis is the development of highly luminescent and photostable trityl radicals. In Chapter I, after an overview on luminescence, the unique optical properties of carbon-centred free-radicals will be introduced, focusing on the strengths and perspectives offered by these molecules in fluorescence microscopy and electroluminescence devices. In Chapter II, a study on the optical properties of the tris(2,4,6-trichlorophenyl)methyl radical (TTM) and perchlorotriphenylmethyl radical (PTM) when used as emitting specie in organic nanoparticles (ONPs) and polymeric films will be presented. Indeed, despite the good knowledge about the luminescence properties of trityl radicals in solution, no systematic studies are reported about the effect of the confinement of radicals in organic rigid matrices. As host systems the optically neutral tris(2,4,6-trichlorophenyl)methane (TTM-αH) and poly(methylmethacrylate) for ONPs and films respectively, have been chosen. Particularly interesting is the case of TTM doped ONPs (TTMd-ONPs) in which, for the first time for a carbon-centred free-radical, it has been observed the formation of excimers. Both systems become particularly interesting because for the first time, excimeric emissions from carbon centered free-radicals will be observed due to the formation of stable and persistent supramolecular radical-pairs. Thanks to their emission in the red-NIR region (650-800 nm), these free-radical excimer-forming materials become promising molecular materials for bioimaging and optoelectronics applications In Chapter III, the processes which explain the association and dissociation of TTM excimers (molecular structure, nature of the host, thermal effects) will be studied. In particular, it will be found that TTMd-ONPs offer the possibility to be employed as cost-effective, ratiometric nanothermometer. In this framework, the ratiometric output of 20% TTMd-ONPs water suspension has been studied in different conditions of polarity, ionic strength and pHs, in order to test its possible applicability as bio thermal sensor. Finally, in Chapter IV it will be presented the synthesis of a new class of radicals, i.e. polybromotriphenylmethyl radicals. This new molecule constitutes the perfect building block for the synthesis of highly luminescent and photostable trityl radicals. In fact, thanks to its three para bromine functionalizations, this new radical allows to easily overcome the poor synthetic versatility of polychlorotriphenylmethyl radicals. Moreover, compared to the analogous chlorinated specie, the tris(2,4,6-tribromophenyl)methyl radical (TTBrM) exhibits a red-shifted absorption and emission, a higher photostability, and it is able to form NIR-excimers when dispersed in ONPs, constituting a promising radical for bio-imaging applications.

APA, Harvard, Vancouver, ISO, and other styles

10

Pinto, Martínez Andrea. "Luminescent gold(I) supramolecular assemblies on materials and biological chemistry." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/672744.

Full text

Abstract:

During the last years, the research group where this Doctoral Thesis has been carried out has been pioneer in the development of different gold(I) complexes and resulting supramolecular assemblages with a wide variety of applications. The starting point of this intensive development of systems is in the study of a gold(I)-alkynyl system with water- soluble phosphines, which gave rise to the formation of a hydrogel. This example was the precedent for an exhaustive study of the aggregation processes of gold(I) complexes, where modifications in the chromophore or the incorporation of charge in the system gave rise to a wide range of morphologies (rods, vesicles, square, stars ...) with different luminescent properties. Taking into account this precedent, this Doctoral Thesis focuses on using the supramolecular chemistry of gold(I) complexes in order to modulate their luminescent properties, taking a further step in the methodology of establishment by the group and designing and investigating new gold(I) compounds and assemblies that present improved properties and are suitable to be studied in different types of applications, ranging from luminescent materials, molecular recognition or biological applications. These complexes have been rationally designed, where the different parts of the molecular structure were selected for a specific application. Phosphines have been chosen as the second coordination site, since they are ligands that can modulate the solubility in different solvents and the nuclearity of the resulting compounds. Carbenes have also been used to introduce planarity into the final compound. A great variety of techniques have been used to demonstrate the correct formation of organic and organometallic compounds (NMR, IR, ESI, and X-ray diffraction). The supramolecular structures obtained have been duly analyzed by DLS, SEM, UV-vis, fluorescence and SAXS.
Durante los últimos años, el grupo de investigación donde se ha realizado esta Tesis Doctoral ha sido pionero en el desarrollo de diferentes complejos de oro(I) y ensamblajes supramoleculares resultantes con una amplia variedad de aplicaciones. El punto de partida de este intensivo desarrollo de sistemas se sitúa en el estudio de un sistema de oro(I)- alquinilo con fosfinas solubles en agua, el cual, dio lugar a la formación de un hidrogel. Este ejemplo fue el precedente de un exhaustivo estudio de los procesos de agregación de los complejos de oro(I), dónde modificaciones en el cromóforo o la incorporación de carga en el sistema dio lugar a un amplio abanico de morfologías (bastoncillos, vesículas, cuadrados, estrellas…) con diferentes propiedades luminiscentes. Teniendo en cuenta éste precedente, ésta Tesis Doctoral se centra en utilizar la química supramolecular de los complejos de oro(I) por tal de modular sus propiedades luminiscentes dando un paso más en la metodología de establecimiento por parte del grupo y de diseñar e investigar nuevos compuestos y ensamblajes de oro(I) que presentan propiedades mejoradas y aptos para ser estudiados en diferentes tipos de aplicaciones, yendo de materiales luminiscentes, reconocimiento molecular o aplicaciones biológicas. Estos complejos han sido racionalmente diseñados, dónde las diferentes partes de la estructura molecular fueron seleccionadas para una aplicación determinada. Como segundo sitio de coordinación se han escogido fosfinas, ya que son ligandos que pueden modular la solubilidad en diferentes disolventes y la nuclearidad de los compuestos resultantes. Los carbenos también han sido utilizados por tal de introducir planaridad en el compuesto final. Una gran variedad de técnicas ha sido utilizada para evidenciar la correcta formación de los compuestos orgánicos i organometálicos (RMN, IR, ESI, i difracción de rayos X). Las estructuras supramoleculares obtenidas han sido debidamente analizadas por DLS, SEM, UV-vis, fluorescencia i SAXS.

APA, Harvard, Vancouver, ISO, and other styles

11

Planelles, Aragó José. "Síntesis one-pot y propiedades fotoluminiscentes de nanocristales semiconductores II-VI dopados con europio (III)." Doctoral thesis, Universitat Jaume I, 2012. http://hdl.handle.net/10803/129003.

Full text

Abstract:

Esta tesis doctoral, que lleva por título: “Síntesis one-pot y propiedades fotoluminiscentes de nanocristales semiconductores II-VI dopados con europio (III)", se enmarca dentro del campo de la nanofotónica, al centrarse en la preparación y caracterización de materiales nanoestructurados cuyas propiedades físicas, especialmente las ópticas, han sido modificadas químicamente. Tal y como el propio título indica, en ella se recopilan los resultados obtenidos en el estudio de nanocristales de CdS y ZnS, cuyas propiedades ópticas son moduladas mediante el dopaje con iones lantánidos, concretamente, Eu3+. La interacción entre los nanocristales semiconductores y los iones lantánidos, responsable de la respuesta óptica exhibida por el material, se trata con profundidad a través de minuciosos estudios espectroscópicos.

Además en el trabajo se describen varias rutas de síntesis adoptadas (sol-gel y precipitación) y optimizadas para la preparación de estos materiales así como la caracterización de su estructura mediante diversas técnicas instrumentales adecuadas para el estudio de materiales en la escala nanométrica.

APA, Harvard, Vancouver, ISO, and other styles

12

Aguiló, Linares Elisabet. "Estructuras supramoleculares de oro(I) con propiedades luminiscentes. Estudios de agregación y aplicaciones." Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/403398.

Full text

Abstract:

Hace unos años, en el grupo de investigación donde se ha realizado esta Tesis Doctoral, se estudió un sistema de oro(I)-alquinilo con una fosfina soluble en agua, que dio lugar a la formación de un hidrogel. Este ejemplo es de destacar, ya que fue el primer trabajo acerca de la formación de un hidrogel con una estructura química tan simple. Las interacciones aurofílicas y otras interacciones débiles estaban involucradas en el proceso de gelificación. Este resultado es el punto de partida de este Tesis Doctoral. El trabajo realizado en esta Tesis Doctoral se ha centrado en la síntesis de diferentes tipos de complejos de oro(I) que contienen la fórmula general [Au(C≡C- org)(PR3)] (org = piridina, cumarina, tetrapirrol) (PR3 = PTA, DAPTA, TPPTS) (fosfinas solubles en agua). Se han introducido cambios en la unidad cromófora (cumarina, tetrapirrol, bipiridina o terpiridina en lugar de la piridina) y se ha estudiado cuidadosamente la formación de complejos iónicos en lugar de neutros con el objetivo de analizar cómo estas modificaciones pueden afectar a los conjuntos supramoleculares resultantes y en sus propiedades luminiscentes. Por otra parte, en los últimos años, se han empleado varias técnicas y métodos para atribuir la presencia de aurofilicidad intra- e intermolecular en solución, en nuestro caso, los experimentos de RMN de 1H llevados a cabo con los complejos que forman hidrogeles a diferentes concentraciones y temperaturas nos han proporcionado información sobre los parámetros termodinámicos implicados en la formación de agregados. Así se ha podido analizar con más detalle cuáles son las fuerzas particulares responsables de la formación de estos hidrogeles organometálicos. También, la técnica SAXS nos ha permitido analizar con más detalle el proceso de agregación que tiene lugar con los complejos derivados de la bipiridina. Más recientemente, el interés en este tipo de compuestos desde el punto de vista biológico está aumentando y los resultados parecen bastante prometedores. De hecho, los informes iniciales recientes sobre la bioactividad de los complejos de oro(I)-alquinilo indican que este tipo de complejos organometálicos ofrecen oportunidades para el desarrollo de nuevos fármacos quimioterapéuticos contra el cáncer y las enfermedades infecciosas. Además, en general, las fuerzas intermoleculares débiles están involucradas en los procesos de reconocimiento molecular, y para ello hemos querido explorar cómo los conjuntos supramoleculares pueden ser modificados en presencia de aniones (principalmente haluros). Los objetivos particulares de esta Tesis Doctoral se relacionan a continuación, juntamente con el capítulo en el que se describen. En el Capítulo 2 se ha sintetizado un nuevo compuesto de oro(I) derivado de la 4- etinilpiridina con una pequeña variación (introducción de grupos acetilo) con respecto al complejo precursor que forma el hidrogel, para ver si tiene un claro efecto sobre las propiedades estructurales y luminiscentes resultantes. También, se han realizado tratamientos térmicos sobre la estructura supramolecular formada para observar la formación de nanopartículas metálicas de oro. En el Capítulo 3, se han estudiado los procesos de agregación que tienen lugar en los complejos de oro(I)-alquinilo derivados de la 4-etinilpiridina mediante diferentes técnicas espectroscópicas, tales como absorción UV-vis, RMN (a diferentes temperaturas y concentraciones) y DLS, para estimar la constante de equilibrio del proceso de agregación y la presencia de interacciones aurofílicas. Se han realizado cálculos computacionales para saber de la existencia de contactos Au-Au. En el Capítulo 4, se han sintetizado complejos catiónicos de oro(I) derivados de la 4-etinilpiridina para observar si forman ensamblajes supramoleculares diferentes respecto a los complejos precursores neutros. También, se ha estudiado cómo el contraión puede modificar la morfología supramolecular resultante. Además, se ha realizado un estudio de cómo se ve afectada la agregación de estos complejos con carga positiva por el disolvente con influencia directa sobre sus propiedades de absorción y emisión, y la morfología global de los agregados. En el Capítulo 5, se han sintetizado cuatro complejos organometálicos de oro(I) que contienen diferentes fosfinas solubles en agua y unidades cromóforas (4- etinilpiridina y propargiloxicumarina) con propiedades luminiscentes. Se han estudiado sus propiedades luminiscentes mediante absorción UV-vis y emisión, así como sus propiedades estructurales mediantes microscopía óptica y electrónica. También, se ha analizado su actividad biológica contra el crecimiento de células tumorales así como sus actividades inhibidoras contra la enzima tiorredoxina reductasa. En el Capítulo 6, se han sintetizado nuevos sistemas organometálicos de oro(I) derivados del [4]calixpirrol con fosfinas solubles en agua, para observar si forman estructuras supramoleculares en agua. Se han estudiado las interacciones intermoleculares con el fin de comprender el empaquetamiento supramolecular resultante. Se han realizado estudios de los procesos de reconocimiento molecular para la detección de haluros y comparado con los resultados previamente estudiados con el ligando libre. En el Capítulo 7, se han sintetizado cuatro complejos de oro(I) derivados de la bipiridina y de la terpiridina con fosfinas solubles en agua. Se han estudiado sus propiedades luminiscentes y estructurales. También, se ha realizado un estudio detallado del proceso de agregación y desagregación en agua y DMSO mediante las técnicas espectroscópicas de RMN, de absorción UV-vis y de emisión, así como la técnica SAXS. En el Capítulo 8, se han sintetizado diferentes nanoestructuras de Au aprovechando las distintas estructuras supramoleculares que forman ciertos complejos de oro(I), mediante la reducción del oro con la presencia de nanopartículas de plata. En el Capítulo 9, se han diseñado y sintetizado nuevos sistemas fotocatalíticos de oro(I) con TiO2 como soporte para la obtención de energía (H2).
A few years ago, in the research group where this Doctoral Thesis was carried out, a gold (I) -alkynyl system was studied with a water-soluble phosphine, which gave rise to the formation of a hydrogel. This example is noteworthy, since it was the first work on the formation of a hydrogel with such a simple chemical structure. Aurophilic interactions and other weak interactions were involved in the gelation process. This result is the starting point of this Doctoral Thesis. The work done in this Doctoral Thesis has focused on the synthesis of different types of gold (I) complexes containing the general formula [Au (C≡C-org) (PR3)] (org = pyridine, coumarin, tetrapyrrole) (PR3 = PTA, DAPTA, TPPTS) (water soluble phosphines). Changes have been made in the chromophoric unit (coumarin, tetrapyrrole, bipyridine or terpyridine instead of pyridine) and the formation of ionic complexes rather than neutral ones has been carefully studied in order to analyze how these modifications can affect supramolecular assemblies And their luminescent properties. On the other hand, in the last years, several techniques and methods have been used to attribute the presence of intra- and intermolecular aurophilicity in solution, in our case, the 1H NMR experiments carried out with the complexes that form hydrogels to different Concentrations and temperatures have provided us with information about the thermodynamic parameters involved in the formation of aggregates. Thus it has been possible to analyze in more detail what are the particular forces responsible for the formation of these organometallic hydrogels. Also, the SAXS technique has allowed us to analyze in more detail the aggregation process that takes place with complexes derived from bipyridine. More recently, the interest in this type of compounds from the biological point of view is increasing and the results seem quite promising. In fact, recent initial reports on the bioactivity of gold (I) -alkynyl complexes indicate that these organometallic complexes offer opportunities for the development of new chemotherapeutic drugs against cancer and infectious diseases. In addition, in general, weak intermolecular forces are involved in molecular recognition processes, and for this we wanted to explore how supramolecular assemblies can be modified in the presence of anions (mainly halides).

APA, Harvard, Vancouver, ISO, and other styles

13

Koutný, Michal. "Vliv teplotních závislostí luminiscence solárních článků." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218584.

Full text

Abstract:

This work deals with determination defects in solar cells using non-destructive methods. Defects are determinating by electroluminescence method and microplasma method in temperature influence. Temperature will be changed by Peltier cells. By using this various temperatures during the testing we can receive more objective results thanks to simulated operation conditions.

APA, Harvard, Vancouver, ISO, and other styles

14

Climent, Biescas Claudia. "Theoretical study of excited states in molecules and molecular aggregates relevant for optoelectronic applications." Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/462831.

Full text

Abstract:

In this thesis, different organic and organometallic molecules with interest for optoelectronic applications have been studied from a computational standpoint. The work presented in this thesis belongs to the molecular quantum chemistry field and in particular to the investigation of the low- lying electronic excited states involved in the target photophysical processes. Chapter 1 is devoted to the study of the absorption process of several organic dyes with potential application in dye-sensitized solar cells (DSSCs). In particular, the influence of the nature of the π- bridge in donor-acceptor dyes has been investigated. The photophysical properties of the dyes are rationalized based on geometrical characteristics and their electronic structure. The charge transfer nature of the optical state has also been investigated with several computational tools. Solvent effects on the absorption of the dye have also been considered and simulated to give an explanation to experimental observations. Chapter 2 deals with phosphorescent Ir(III) complexes that have interest as triplet emitters for organic light-emitting diodes (OLEDs). All the studies presented in this chapter have been done in collaboration with the experimental group of Prof. Inamur Rahman Laskar at the Birla Institute of Technology and Science (BITS) in Pilani, India, and his coworkers. After our first collaborations, we became interested in Ir(III) complexes exhibiting aggregation induced emission (AIE). This is a very interesting phenomenon where the emission intensity is enhanced in the solid state compared to dilute solution. Systems presenting the AIE are very attractive for a wide range of applications other than OLEDs. In this chapter, a section is devoted exclusively to analyze the evolution of this field and the principal mechanisms proposed to explain this phenomenon. It does not pretend to be a complete review from the literature, but rather a critical assessment with personal thoughts on the subject. As for the results, we were interested to understand how the photophysical properties are influenced by the presence of different ligands on the Ir(III) complexes and by the presence of intermolecular interactions. The absorption and emission of the studied complexes has been characterized and different approaches have been taken to give an explanation to experimental observations from our partners. In Chapter 3 a study on the photophysics of sulfur bridged naphthalene dimers is presented. This work was partially done during a research stay in the group of Prof. Mario Barbatti at the Institut de Chimie Radicalaire in Marseille (France). Herein we were interested in explaining the dependence of the photoluminescence of the aforementioned dimers on the oxidation state of the sulfur atom at the bridge. Experimental work on these compounds and related ones had been previously reported. An explanation for the different luminescence however was not given for the naphthalene dimers. In this chaper we have tackled this problem by characterizing the excited states and crossings between the ground and first excited state PESs.
En aquesta tesi s’han aplicat els mètodes de la química quàntica molecular per estudiar des del punt de vista de la fotofísica, les característiques principals de l’estructura electrònica d’un conjunt de molècules orgàniques i organometàl·liques amb interès per aplicacions optoelectròniques. En particular, s’han estudiat per una part colorants orgànics amb propietats òptiques adients per ser emprats com a sensibilitzadors en cel·les solars sensibilitzades amb colorant (DSSCs en anglès). En una altra direcció, s’han investigat una sèrie de complexos d’Ir(III) amb potencial aplicació com a compostos emissors en díodes orgànics emissors de llum (OLEDs en anglès). Aquests complexos també presenten el fenomen d’emissió induïda per agregació (AIE en anglès), en el que la intensitat d’emissió augmenta en l’estat sòlid en comparació a la feble o inexistent luminiscència mesurada en dissolucions diluïdes. Els sistemes que presenten AIE son molt atractius per un gran varietat d'aplicacions. En aquesta tesi, una secció s’ha dedicat exclusivament a analitzar l’evolució d’aquest camp i dels principals mecanismes proposats per explicar el fenomen de l’AIE, aportant una valoració crítica amb opinions personals sobre el tema en qüestió. Finalment, aquest treball inclou també la investigació computacional de les propietats fotofísiques de dímers de naftalè enllaçats per un pont basat en sofre, amb potencial aplicació en dispositius orgànics fotovoltaics (OPVs en anglès) i OLEDs. En aquest cas estàvem interessats en explicar la dependència de la fotoluminescència dels dímers estudiats amb l’estat d’oxidació de l’àtom de sofre del pont que connecta els monòmers de naftalè. Aquesta qüestió s’ha abordat caracteritzant els estats excitats i els encreuaments entre l’estat fonamental i el primer estat excitat.

APA, Harvard, Vancouver, ISO, and other styles

15

Martín, Rodríguez Rosa. "Síntesis, caracterización estructural y estudio espectroscópico de materiales nanocristalinos y microcristalinos." Doctoral thesis, Universidad de Cantabria, 2011. http://hdl.handle.net/10803/10645.

Full text

Abstract:

El trabajo resumido en esta tesis se ha llevado a cabo dentro del grupo de Altas Presiones y Espectroscopia de la Universidad de Cantabria y tiene dos objetivos principales. Por un lado, se han estudiado las propiedades ópticas de distintos iones de metales de transición y tierras raras en diversas redes aislantes. Se han realizado medidas experimentales de luminiscencia, absorción, tiempo de vida y espectroscopia resuelta en tiempo. Concretamente, uno de los objetivos principales ha sido establecer los mecanismos responsables de la luminiscencia de upconversion de los materiales estudiados, y los requerimientos estructurales para aumentar su eficiencia. Para ello se han comparado diversos métodos de síntesis así como diferentes concentraciones de impurezas. Asimismo, se han investigado transiciones de fase a alta presión en semiconductores con tamaño de partícula en el rango de los nanómetros mediante absorción óptica, espectroscopia Raman y difracción de rayos X. La síntesis de las muestras representa también una parte muy importante de este trabajo.
This work has been performed within the High Pressure and Spectroscopy group at the University of Cantabria. The aim of this thesis is two-fold; firstly, this work has been devoted to the study of the microscopic origin of the optical properties of diverse transition metal and rare-earth ions in different insulating host lattices. Concretely, one of the main goals has been to establish the mechanisms responsible for the upconversion luminescence properties of the studied materials, as well as the structural requirements to increase their quantum efficiency. Different synthesis methods and impurity concentrations have been compared. Secondly, phase transitions under high pressure in semiconductor nanocrystals or quantum dots have been studied by means of optical absorption, Raman spectroscopy and X-ray diffraction. Besides, the synthesis of the samples is a remarkable point since we have prepared ourselves all the samples studied in this thesis work.

APA, Harvard, Vancouver, ISO, and other styles

16

Těšík, Jan. "Luminiscence polovodičů studovaná rastrovací optickou mikroskopií v blízkém poli." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-320110.

Full text

Abstract:

This work is focused on the study of luminescence of atomic thin layers of transition metal chalkogenides (eg. MoS2). In the experimental part, the work deals with the preparation of atomic thin layers of semiconducting chalcogenides and the subsequent manufacturing of plasmonic interference structures around these layers. The illumination of the interference structure will create a standing plasmonic wave that will excite the photoluminescence of the semiconductor. Photoluminescence was studied both by far-field spectroscopy and near-field optical microscopy.

APA, Harvard, Vancouver, ISO, and other styles

17

Krasheninnikova, Maria Alieva. "Adipose tissue mesenchymal stromal cells as therapeutic vehicles against glioblastoma." Doctoral thesis, Universitat de Barcelona, 2012. http://hdl.handle.net/10803/97086.

Full text

Abstract:

Lately adipose tissue mesenchymal stem cells (hAMSCs) have emerged as cellular vehicles for therapy of solid tumors, due to their ease of isolation and manipulation, and wound/tumor homing capacity. HAMSCs have been successfully used in suicide gene therapy, employing the prodrug activating system based on Herpes simplex virus type I thymidine kinase (HSV-TK)/ganciclovir (GCV). In the current study we demonstrate an effective model of glioblastoma therapy based on the use of genetically modified hAMSCs and in vivo monitoring of tumor and therapeutic cells. Due to the capacity of photons to pass through living tissue, non-invasive monitoring by bioluminescence imaging has become a cutting edge technology for the study of ongoing biological processes in small lab animals. This technique uses photoproteins as cell reporters that generate light photons as byproducts of chemical reaction. Luciferases catalyze the oxidation of a substrate (luciferin) in the presence of ATP and oxygen to generate oxiluciferin, ADP and light photons. In spite of the apparent opacity of tissues, light can be detected at several millimeters of depth in live animals. Combination of several types of luciferases allows simultaneous monitoring of different cell populations proliferation or differentiation. We stably transduced hAMSCs for expression of Renilla luciferase, HSV-TK and red fluorescent protein, generating RLuc-R-TK-AMSC and U87MG human malignant glioma cells for expression of Firefly luciferase and green fluorescent protein, generating Pluc-G-U87 cells. SCID mice were stereotactically implanted in the brain first with Pluc-G-U87 and RLuc-R-TK-AMSC afterwards. Mice were subjected to GCV treatment and the therapeutic process was evaluated in real time. Tumor response was monitored in vivo by BLI. Therapeutic cell differentiation was assessed by labeling the above Renilla luciferase expressing hAMSCs with a Firefly luciferase reporter regulated by the CD31, endothelial specific promoter and in vivo monitorization. Endothelial lineage differentiation of hAMSC was impaired, by Notch1 shRNA, and therapeutic effect was assessed by BLI monitorization of tumor response. In our model of therapy, we show that tumor size can be continuously monitored by BLI and is significantly reduced (99,9% relative to control untreated tumours) by repeated inoculations in the tumours with thymidine kinase expressing hAMSCs followed by the prodrug ganciclovir. Moreover treatment resulted in a significant prolongation of survival time. In addition, the combination of BLI and confocal microscopy analysis of therapeutic cells suggests that efficient tumor eradication results from hAMSCs homing to tumor vessels, where they differentiate to endothelial cell lineage, intensifying their cytotoxic effect by destroying tumor vasculature and negating nutrient supply. Besides, hAMSCs endothelial differentiation inhibition resulted in an inefficient therapeutic effect compared to normal hAMSC (64% vs 6% respectively). Close association between hAMSCs and gliomas stem cells integrated in the tumor vascular system seems to be essential for an effective tumor reduction. We suggest that efficient tumor eradication is due to hAMSCs endothelial differentiation and tube location that intensifies its cytotoxic function, destroying tumor vasculature and inhibiting nutrient supply to tumor cells. Thus we propose adipose tissue hAMSCs as useful vehicles for clinical applications to deliver localized therapy to glioma surgical borders after tumor resection.

APA, Harvard, Vancouver, ISO, and other styles

18

Moralles, Vagner Antonio [UNESP]. "Síntese e caracterização de composto de coordenação com ligante de produto natural." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/150211.

Full text

Abstract:

Submitted by VAGNER ANTONIO MORALLES null (vagner_gner@yahoo.com.br) on 2017-04-08T20:13:43Z No. of bitstreams: 1 MORALLES, V.A. DISSERTAÇÃO.pdf: 5606116 bytes, checksum: 5a412f90292a50233a6a7f9fc513ad74 (MD5)
Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-04-17T15:00:36Z (GMT) No. of bitstreams: 1 moralles_va_me_araiq.pdf: 5606116 bytes, checksum: 5a412f90292a50233a6a7f9fc513ad74 (MD5)
Made available in DSpace on 2017-04-17T15:00:36Z (GMT). No. of bitstreams: 1 moralles_va_me_araiq.pdf: 5606116 bytes, checksum: 5a412f90292a50233a6a7f9fc513ad74 (MD5) Previous issue date: 2017-03-08
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Alguns compostos orgânicos de origem natural apresentam grande interesse para aplicação médica devido suas atividades biológicas como antioxidante, antiviral, antimicrobiano, antitumoral, entre outras. Destes estes compostos, alguns se destacam por apresentarem a possibilidade de agir como ligante em compostos de coordenação. Para o desenvolvimento desse projeto de pesquisa, em especial, foram selecionados os ligantes 3,5,7,3’,4’- pentahidroxiflavona (quercetina), ácido 3,4,5-triidroxibenóico (ácido gálico), ácido (E)-3fenil- 2-propenóico (ácido cinâmico) e (E)-3-(4-hidroxifenil)-2-propanoico (ácido p-cumárico). Pretende-se, portanto, maximizar as atividades antioxidantes e antitumorais destes ligantes de origem natural, por meio da complexação em compostos de coordenação. Além disso, estudar as propriedades estruturais e ópticas dos complexos obtidos. O desenvolvimento dessa pesquisa permitiu encontrar uma relação entre a estrutura do ligante e suas propriedades ópticas quando excitados com radiação ultravioleta e raios X. Conseguiu-se também levantar algumas hipóteses sobre a potencialidade de utilização destes compostos de coordenação como filtros solares.
Some organic compounds of natural origin are of great interest for medical application due to their biological activities as antioxidant, antiviral, antimicrobial, antitumor, among others. Of these compounds, some are notable for their ability to act as a binder in coordination compounds. For the development of this research project, in particular, the binders were selected quercetin (2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-chromen-4-one), Cinnamic acid (3-phenyl-2-propenoic acid) and p-coumaric acid ((E)-3-(4-hydroxyphenyl)-2-propenoic acid). It is therefore intended to maximize the antioxidant and antitumor activities of these naturally occurring binders by complexing into coordination compounds. In addition, to study the structural and optical properties of the complexes obtained. The development of this research allowed to find a relation between the structure of the binder and its optical properties when excited with ultraviolet radiation and X-rays. It was also possible to raise some hypotheses about the potential of using these coordination compounds as sunscreens.

APA, Harvard, Vancouver, ISO, and other styles

19

López, Vidrier Julià. "Silicon Nanocrystal Superlattices for Light-Emitting and Photovoltaic Devices." Doctoral thesis, Universitat de Barcelona, 2015. http://hdl.handle.net/10803/334396.

Full text

Abstract:

During the last decades, silicon nanocrystals have focused great attention due to the size-dependent physical properties they present, attributed to the quantum confinement effect. This, added to the bulk silicon compatibility with the well-established microelectronics technology and the low mining and manipulation costs this material presents, makes silicon a potential candidate for the growing photonics and optoelectronics fields. In particular, the tunnability of the electronic properties of silicon nanocrystals can be reached by controlling the nanocrystal size. This has been recently achieved by means of the superlattice approach, consisting of the alternated deposition of ultra-thin (2-4 nm) stoichiometric and silicon-rich layers of a given silicon-rich material. After a high-temperature annealing treatment, the silicon excess precipitates and crystallizes in the final form of nanocrystals, whose properties strongly depend on the fabrication process. Consequently, an ordered arrange of size-controlled nanocrystals (the superlattice) is obtained. In this Thesis Project, the structural, optical, electrical and electro-optical properties of silicon nanocrystal superlattices have been studied, using two different silicon-based materials as host matrices: silicon oxide and silicon carbide. The fabrication of these material systems has been carried out at different European institutions, specialists in the controlled deposition of nm¬thick films. Aiming at the nanocrystal superlattices characterization, different experimental techniques have been employed, which yield structural (transmission and scanning electron microscopies, X-ray diffraction), optical (optical absorption, photoluminescence and Raman scattering spectroscopies) and electrical / electro-optical (current versus voltage analysis in dark and under illumination, and electroluminescence, electro-optical response and light-beam induced photocurrent spectroscopies) information. From the material's point of view, the optimum structural properties that allow an almost perfect nanocrystal arrangement, size control and crystalline degree have been determined, always aiming at an optimum light emission and/or light absorption. Within this frame, fundamental studies have been performed to assess the crystalline degree of the nanostructures (confirming an atomic-thin transition layer between the crystalline nanocrystal core and the surrounding matrix), and to carefully inspect the controversial origin of luminescence within the nanocrystals when embedded in a silicon oxide matrix; as well, the structural conditions under which size-confinement of nanocrystals is reached when embedded in silicon carbide are reported. Once the best structural and optical properties from silicon nanocrystal superlattices were found, these material systems have been employed as active layers for light emitting and light converter (i.e. photovoltaic) devices. In oxide-based systems, the mechanisms that govern charge transport through the superlattices have been studied, and impact ionization has been hypothesized as the main electroluminescence excitation mechanism according to the experimental observations. In addition, the structural conditions (sublayer thicknesses, silicon-rich layer stoichiometry) that yield a maximum electroluminescence efficiency have been determined. Regarding silicon nanocrystals embedded in silicon carbide, a correlation has been established between the charge photogeneration and extraction when acting as an absorber material, which allowed assessing the structural conditions that maximize charge transport while minimizing the non-desirable recombination. Finally, via spectral response measurements, quantum confinement of excitons within silicon nanocrystals has been reported in silicon carbide matrix for the first time. In conclusion, the study on silicon nanocrystal superlattices developed within the present Thesis Project reveals the potential of silicon oxide as host matrix for silicon nanostructures to be used as light-emitting devices; instead, silicon carbide has proved a more suitable host material for photovoltaic applications, which sheds light to the future application of silicon nanocrystals as the top cell of an all-Si tandem cell.
Els nanocristalls de silici han esdevingut objecte d'estudi durant l'últim quart de segle, degut a què presenten, a causa de l'efecte de confinament quàntic, unes propietats físiques dependents de la seva mida. A més, la compatibilitat del silici massiu amb la ben establerta tecnologia microelectrònica juga en favor de la seva utilització i el seu desenvolupament per a futures aplicacions en el camp de la fotònica i l'optoelectrónica. El control del creixement de nanocristalls de silici es pot dur a terme mitjançant el dipòsit de superxarxes d'entre 2 i 4 nm de gruix, on capes de material estequiomètric basat en silici s'alternen amb altres de material ric en silici. Un posterior procés de recuit a alta temperatura permet la precipitació de l'excés de silici i la seva cristal.lització, tot originant una xarxa ordenada de nanocristalls de silici de mida controlada. En aquesta Tesi, s'han estudiat les propietats estructurals, òptiques, elèctriques i electro-òptiques de superxarxes de nanocristalls de silici embeguts en dues matrius diferents: òxid de silici i carbur de silici. Amb tal objectiu, s'han emprat tot un seguit de tècniques experimentals, que comprenen la caracterització estructural (microscòpia electrònica de transmissió i d'escombrat, difracció de raigs X), òptica (espectroscòpies d'absorció òptica, de fotoluminescència i dispersió Raman) i elèctrica / electro-òptica (caracterització intensitat-voltatge en foscor o sota il.luminació, electroluminescència, resposta electro-òptica), entre d'altres. Des del punt de vista del material, s'han estudiat les propietats estructurals òptimes per tal d'obtenir un perfecte ordenament en la xarxa de nanocristalls, una major qualitat cristal.lina i unes propietats d'emissió òptimes. L'optimització del material s'ha dut a terme en vistes a la seva utilització com a capa activa dins de dispositius emissors de llum i fotovoltaics, l'eficiència dels quals ha estat monitoritzada segons els diferents paràmetres estructurals (gruix de les capes nanomètriques involucrades, estequiometria, temperatura de recuit). Finalment, els nanocristalls de silici embeguts en òxid de silici han demostrat un major rendiment com a emissors de llum, mentre que una matriu de carbur de silici beneficia les propietats d'absorció i extracció (fotovoltaiques) del sistema.

APA, Harvard, Vancouver, ISO, and other styles

20

Ramírez, Joan Manel. "Rare Earth-Doped Silicon-Based Light Emitting Devices: Towards new Integrated Photonic Building Blocks." Doctoral thesis, Universitat de Barcelona, 2015. http://hdl.handle.net/10803/299365.

Full text

Abstract:

This thesis presents the work carried out towards the implementation of RE-doped Si-based light emitting devices as integrated optoelectronic building blocks for Silicon Photonics. This work spans from the fundamentals such as the structure, the morphology of active layers containing Si-ncs and/or RE ions or the origin of the EL emission under different voltage excitations, to the development of advanced Si-based light emitting devices, providing insights on the device design, mask layout, device fabrication and the optoelectronic characterization. Also, novel layer architectures are proposed to overcome some of the inherent limitations of studied devices, paving the way towards efficient and reliable Si-based light emitting devices. This thesis is divided in two main blocks: one dedicated to the study of Er-doped Si-based light emitting devices emitting at 1.54 µm for on-chip optical data routing, and another one focussed on the structural and luminescence properties of Tb3+ and Ce3+ doped silicon oxide and oxynitride thin films with different layer compositions as enabling materials for sensing and RGB micro display applications. Also, different multilayer architectures containing alternated RE-doped single layers are explored.
Aquesta tesi presenta el treball dut a terme en la implementació de dispositius luminescents basats en silici i dopats amb terres rares pel desenvolupament de nous pilars optoelectrònics fonamentals compatibles amb la fotònica del silici. Aquest treball abasta des dels aspectes més fonamentals tals com l’estructura, la morfologia de les capes actives que contenen nano-cristalls de silici i/o ions de terres rares o l’estudi de l’origen de l’electroluminescència dels dispositius quan són polaritzats per diferents voltatges alterns, fins al desenvolupament de nous dispositius avançats basats en silici. En aquest cas, l’estudi portat a terme bé acompanyat d’una descripció detallada del disseny de cada dispositiu, el disseny de la màscara de procés elaborada especialment per a la fabricació dels dispositius en cas que sigui necessari, així com el procés de fabricació dels mateixos i una caracterització optoelectrònica detallada amb les pertinents conclusions al final de cada capítol. També, al final d’aquesta tesi es proposen nous dissenys i arquitectures de dispositiu que pretén establir un mapa de ruta per millorar els dispositius estudiats en aquest tesi, i que està basat en l’experiència adquirida durant els quatre anys d’investigació en dispositius electroluminescents basats en silici.

APA, Harvard, Vancouver, ISO, and other styles

21

Berencén, Ramírez Yonder Antonio. "Rare earth- and Si nanostructure-based light emitting devices for integrated photonics." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/285453.

Full text

Abstract:

This thesis presents experimental work on developing rare-earth ions and Si nanostructures as a material platform for light emitting devices (LEDs) in the visible and near-infrared range. The realization of the different electroluminescent devices, based on a single, bi- or tri-layer approach of silicon oxide and/or silicon nitride co-doped or not with rare earth ions, is successfully performed. Several complementary metal-oxide-semiconductor (CMOS) compatible fabrication techniques such as co-magnetron sputtering, plasma-enhanced chemical vapor deposition (PECVD), low-pressure chemical vapor deposition (LPCVD) and ion implantation are used. By using characterization techniques such as time of flight secondary ion mass spectrometry (TOF-SIMS), secondary ion mass spectrometry (SIMS), X-ray photoelectron spectroscopy (XPS), energy-filtered transmission electron microscopy (EFTEM), focused ion beam (FIB) and ellipsometry, the structural and compositional properties of the studied active layers are determined. In addition, electro-optical properties at room and at high temperatures (25 0C – 300 0C) under quasi-static and dynamic regimes are studied in both visible and near-infrared spectral region. Typically, the used electro-optical techniques have been current-voltage, capacitance-voltage, charge to breakdown, electroluminescence (EL)-current, EL-voltage and time-resolved EL.
Esta tesis presenta un trabajo experimental en el desarrollo de iones de tierras raras y nanoestructuras de Si como plataforma de materiales para dispositivos de emisión de luz (LEDs) en el rango visible e infrarrojo cercano. Se han fabricado diferentes dispositivos electroluminiscentes basados en capas simples, dobles o triples de óxido de silicio y/o nitruro de silicio dopados o no con tierras raras. Para ello se han empleado varias técnicas de fabricación compatibles con la tecnología CMOS; a saber, depósito de vapor químico asistido por plasma (PECVD), pulverización catódica mediante magnetrón, depósito de vapor químico a baja presión (LPCVD) e implantación de iones. Así mismo, las propiedades estructurales y de composición de las capas fabricadas han sido determinadas mediante el uso de técnicas de caracterización tales como TOF-SIMS, SIMS, XPS, EFTEM, FIB y elipsometría. Además, a temperatura ambiente y altas temperaturas (25 0C – 300 0C) se han estudiado las propiedades electro-ópticas en los regímenes cuasi-estático y dinámico. Por lo general, las técnicas electro-ópticas empleadas fueron corriente-voltaje, capacitancia-voltaje, estudio de carga hasta la ruptura, electroluminiscencia (EL)-corriente, EL-voltaje y EL resuelta en tiempo.

APA, Harvard, Vancouver, ISO, and other styles

22

Juvert, Sández Joan. "Development and optimization of silicon based light sources for integration into a sensor platform." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/275940.

Full text

Abstract:

We have characterized electroluminescent devices based on silicon rich oxide and/or silicon rich nitride. We have discussed the photoluminescence and structural characterization of the active layers and the electrical and electroluminescent characterization of full devices. We have noted that the electroluminescence can appear in the form of discrete points scattered across the active area of the devices, in the form of emission along the rim of the active area, or homogeneously distributed across the area. These different kinds of emission have been related to the optical and electrical properties of the devices. In the two former cases, the electroluminescence comes with high current densities,of the order of 1 A/cm2, and low efficiencies of the order of 10-8. On the other hand, the homogeneous emission comes with lower current densities, of the order of 0.01 A/cm2, and better efficiencies, in the range 10-7–10-5. We have concluded that the homogeneous emission is optimal in terms of efficiency. Furthermore, a simple model has been proposed to explain the appearance and occasional coexistence of the different kinds of emission. The effect of a nitride layer on top of the SRO has been explored, concluding that it helps in achieving a uniform conduction that favors the homogeneous emission in the active layer. The conductivity states of the active layer associated with the different kinds of emission have been related with its CV behavior. The results of the study show that the homogeneous emission corresponds to well behaved CV curves, whereas the emission through points does not. The injection mechanisms in PECVD and ion implanted samples have been studied, concluding that no single emission mechanism can account for the injection at all regimes in the studied range of electric fields. Fowler-Nordheim or trap assisted tunneling have been found to play a significant role in PECVD samples. In implanted samples, Fowler-Nordheim dominates at low fields, whereas Poole-Frenkel is more likely to be the dominant mechanism at higher fields. Comparison of the photoluminescence and electroluminescence spectra of bilayers SRO/SRN, allows us to conclude that each layer contributes a different band in the total emission, which results in a wider distribution of the energy across the visible spectrum. The comparison between the photoluminescence and electroluminescence has revealed massive differences in their spectra, which have been attributed to interference effects. A computer software based in the Crawford method for the study of the interference effects in multilayer stacks has been presented. The program has been used to quantitatively study the interference effects in the emission of our devices. We can conclude that the photoluminescence and electroluminescence spectra are the same despite their apparent difference. Our analysis has also made it apparent that a quantitative understanding of the interference effects in the system is important in order to draw valid conclusions regarding the origins of the luminescence. We have presented the design, fabrication and characterization of a CMOS compatible optical transceiver, and two main challenges in the integration of the emitter, waveguide and detector have been successfully overcome, namely achieving a reasonably flat and uniform silicon oxide trench and a good detector. In the end, the transceiver has not worked as expected, most likely due to a poor SRN emitter. More work is required in order to better control the fabrication process of the SRN layers. However, we believe the basic design to be valid, given the low electrical coupling detected between the emitter and the detector components of the transceiver.
Aquesta tesi presenta un estudi de les propietats òptiques de capes d'òxid de silici enriquit en silici (SRO) i nitrur de silici enriquit en silici (SRN) que han sofert un procés tèrmic d'alta temperatura. Aquest procés indueix la creació de nanoaglomerats de silici en la matriu dielèctrica. Aquestes nanoestructures de silici presenten una superior eficiència en l'emissió respecte al silici en bloc, i a més a més emeten en el visible en comptes de l'infraroig. Això és interessant per a l'obtenció de dispositius fotònics integrats basats en silici que poden ser fabricats monolíticament en un procés compatible amb la tecnologia CMOS que domina la indústria microelectrònica. A més a més, hem estudiat les propietats òptiques i elèctriques de dispositius metall-aïllant-semiconductor en les quals l'aïllant és una capa d'SRO o SRN amb nanoaglomerats de silici. N'hem mesurat paràmetres d'interès com ara l'eficiència de conversió d'energia elèctrica-òptica o la potència òptica, i n'hem estudiat els mecanismes d'injecció que hi tenen lloc. S'han identificat tres tipus diferents d'emissió: per punts, per la vora del dispositiu, i emissió homogènia, i hem determinat que l'emissió homogènia és la més adecuada pel que fa a l'eficiència dels dispositius. Hem desenvolupat un programa que permet el càlcul de les interferències òptiques que tenen lloc als sistemes multicapa que conformen els dispositius estudiats, i que distorsionen l'espectre observat respecte al que les capes realment emeten. L'habilitat de poder calcular aquests efectes ens permet, en molts casos, eliminar l'efecte de les interferències i determinar l'autèntic espectre d'emissió de les capes i per tant estar en millors condicions d'assignar l'emissió als mecanismes correctes. Finalment, hem proposat un prototip per a un transceptor en el qual l'emissor, la guia d'ones i el detector estan integrats monolíticament en un procés CMOS. Hem fabricat el dispositiu i l'hem caracteritzat. Tot i que no hem aconseguit acoblament òptic entre l'emissor i el detector, creiem que el disseny bàsic queda validat, ja que els principals obstacles en l'obtenció del dispositiu han sigut superats amb èxit.

APA, Harvard, Vancouver, ISO, and other styles

23

Zdražil, Lukáš. "Příprava grafenových kvantových teček a studium jejich vlastností." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2018. http://www.nusl.cz/ntk/nusl-376826.

Full text

Abstract:

Current methods for preparing graphene quantum dots (GQDs) rely on oxidation and reducing agents or require energy-intensive and technologically demanding preconditions. Applying microwave expansion and liquid phase exfoliation (LPE) in a sample of graphite powder enabled us to prepare GQDs that exhibit strong luminescence in the blue region of the visible spectrum. The proposed technique for synthesizing GQDs is energetically undemanding and does not necessitate additional chemical components.

APA, Harvard, Vancouver, ISO, and other styles

24

Stojan, Radek. "Luminiscenční diagnostika fotovoltaických článků." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-385281.

Full text

Abstract:

Diagnostic of photovoltaic cells defects is one of the key step in production. This dissertation thesis deals about diagnosis of photovoltaic cells by radiative recombination of electron - hole pairs. This radiative recombination is known as luminescence. Diagnostic methods using this local light emission in infrared region have innovative potential. The method of electroluminescence is one of the most widely used luminescence methods whose modifications are applied across the industry, especially in semiconductors. The main area of this thesis research is focused on non-destructive analysis of radiated infrared radiation of monocrystalline and polycrystalline solar cells in various modifications of standard electroluminescence method. In this research there are used two types of CCD cameras are used as luminescent radiation detectors. Method of photon emission microscopy is used for magnification element. Local light emission inspection by microscopy should have benefit to qualitative evaluation of solar cells defects. Radiation emitted by the solar cell has a wave character. This fact brings the potential of using some of the characteristics of the waves. We are talking about the intensity and mainly about new characterization by polarization during the detection of defects in the solar cell surface. Innovation of the measuring workplace of the standard electroluminescence method to use polarization analysis is one of the goals of this dissertation thesis.

APA, Harvard, Vancouver, ISO, and other styles

25

Šimek, Daniel. "Automatizace optické sestavy pro časově rozlišitelnou spektroskopii." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443724.

Full text

Abstract:

Time-resolved spectroscopy is a modern method enabling the analysis of the dynamics of quantum luminescence transitions. This method uses ultra-fast light pulses to study materials, which makes it possible to observe the time evolution of luminescence quenching and thus provides additional information for static absorption and emission spectroscopy. This diploma thesis deals with the automation of the optical setup used in the Optical and Plasmonic Laboratory at Ceitec Nano for performing time-resolved spectroscopy. As part of the work, an application was created enabling communication with 13 devices used in the laboratory. The application automates already performed measurements, and in addition enables the scanning of samples, which was not possible due to time constraints due to the manual control of the stage movement. At the end of the work, test measurements are performed, with a discussion of their effectiveness and time savings for the user.

APA, Harvard, Vancouver, ISO, and other styles

26

Shrestha, Kristina. "Time-Resolved Temperature Measurements and Thermal Imaging using Nano-Thermometers in Different Environments." Ohio University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1593706274306985.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Jedlička, Jindřich. "Bezkontaktní měření teploty pomocí luminiscenčních materiálů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417165.

Full text

Abstract:

This diploma thesis deals with noncontact temperature measurement using luminescent materials. In the theoretical part of the thesis, luminescent materials were selected on the basis of a literature review with respect to sensitivity and operating temperature range. In the experimental part of the thesis, photoluminescence of CdSe/ZnS and GaAs quantum dots for various temperatures was measured and the relative change of luminescence parameters such as emission peak position, intensity, intensity ratio of two emission peaks, and lifetime of luminescence were determined from the measurements in agreement with expectations according to the literature. Achieving high spatial resolution would be made possible by measuring cathodoluminescence, where the luminescence spectra are obtained with an order of magnitude higher spatial resolution. These measurements and the influence of electron beam on the luminescence quality of selected materials will be subject of further experimental study.

APA, Harvard, Vancouver, ISO, and other styles

28

Pavelka, Radek. "Detekce nánosu UV lepidla." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377342.

Full text

Abstract:

This diploma thesis focuses on a design of camera control system used for detecting defects, appearing during a UV luminescent glue application on the bottom of a paper bag. As a part of this thesis, an application was developed, using Baumer VCXG-53C industrial camera, implementing two dierent control methods - 2D cross correlation image pattern matching based on previously user defined pattern and glue area size measuring based on binary segmented image. The result of this work is a fully developed control system, prepared to be put into operation at the customer’s production line.

APA, Harvard, Vancouver, ISO, and other styles

29

Marčík, Silvestr. "Detekce defektů solárních článků pomocí systému využívajcího elektroluminiscenci." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-318496.

Full text

Abstract:

The master thesis focuses primarily on issues of photovoltaic cells in terms of their defects. The introductory part deals with the history of photovoltaics, their introduction into practice and finally an explanation of the photoelectric effect itself. The thesis also describes photovoltaic cells themselves. It explains their principle, advantages, disadvantages and the creation of photovoltaic systems. A substantial part of the work is focused on the topic of detection of defects using luminescent methods. Subsequently, it describes procedural defects arising from the improper handling of already manufactured products. The final part deals with the main topic of the work, which is a detection using luminescence methods and it also mentions the non-luminescence method LBIC. The practical part of the master thesis contains the analysis of the current solution and of the subsequent proposal of solution using a low cost camera. It describes how to modify the camera, verify its spectral sensitivity using a spectrometer and measure the sensitivity of the CMOS sensor. The conclusion is focused on verifying the functionality of the proposed solution on different sources of infrared radiation and photovoltaic panels themselves.

APA, Harvard, Vancouver, ISO, and other styles

30

Richter, Vladimír. "Analýza fotovoltaických článků pomocí fotoluminiscence." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220964.

Full text

Abstract:

This diploma thesis deals with the issues of photovoltaic cells. The main aim of this thesis is to introduce the principles of operation of solar cells and methods of detection of defects affecting their quality. The first part is about the functional properties of silicon cells and it also examines the possibilities of detecting the defects of these structures. It also describes the most commonly used modern diagnostic methods. In the next part, practical tests of photovoltaic cells using the methods electroluminescence and photoluminescence are performed. These methods are based on the excitation of luminescence radiation of the silicon material by the external light source.

APA, Harvard, Vancouver, ISO, and other styles

31

BRADOVÁ, Barbora. "Luminiscence ve výtvarné výchově (Prakticko-teoretická práce)." Master's thesis, 2011. http://www.nusl.cz/ntk/nusl-55005.

Full text

Abstract:

The goal of this diploma thesis is to illustrate conception of luminiscence, clear up basic technical aspects of this effect and show up the possibilities of aplication in art education lectures at primary schools. This work contains theoretical and practical part. Theoretical part is focused on history, basic principles and technics of luminiscence in arts its current position and its wordl and bohemian representatives. Practical part contains real application of luminiscence in art education lectures and its possible transfer to other subjects as physics, chemistry and biology.

APA, Harvard, Vancouver, ISO, and other styles

32

Kořínek, Miloslav. "Luminiscence Study of Excitation Energy Transfer beween Porphyrins and Oxygen." Doctoral thesis, 2006. http://www.nusl.cz/ntk/nusl-266011.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

Garni, Brad. "Investigation of semiconductor optoelectronic surfaces with scanning tunneling microscopy and scanning tunneling luminiscence." 1996. http://catalog.hathitrust.org/api/volumes/oclc/36553610.html.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Araikum, Shawn. "Thermally and optically stimulated luminescence in synthetic diamond." Thesis, 2016. http://hdl.handle.net/10539/21357.

Full text

Abstract:

This study investigated the photo-excitation and thermoluminescence properties of diamonds which were synthesised primarily for thermoluminescence dosimetry. For investigations of thermally stimulated processes occurring in these crystals an analysis of the thermoluminiscence & low spectra and the temperature dependent isothermal decay spectra was undertaken [Abbreviated abstract. Open document to view full version]
GR2016

APA, Harvard, Vancouver, ISO, and other styles

35

Sutrová, Veronika. "Optimalizace nových aktivních povrchů tvořených soubory plasmonických nanočástic pro studium SERS, SERRS a povrchem modifikované luminiscence vybraných molekul." Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-331785.

Full text

Abstract:

Two types of 3-dimensional (3D) Ag nanosponge aggregates were prepared and tested as samples for surface-enhanced Raman scattering (SERS) and as active surfaces for surface- enhanced luminescence. 3D Ag nanosponge aggregates were assembled from 2D fused fractal aggregates (D = 1.87 ± 0.02) prepared by modification of Ag nanoparticle (NP) hydrosol resulting from the reduction of AgNO3 by NH2OH·HCl. For SERS measurements, 3D Ag nanosponge aggregates with incorporated [Ru(bpy)3]2+ cations and chloride anions were prepared and overlayed by a thin layer of aqueous phase. For SEL measurements, the 3D Ag nanosponge aggregates were assembled from fused fractal aggregates of chloride- modified Ag NPs. After preparation the active surface was overlayed by a 1×10-5 M aqueous solution of [Ru(bpy)3]2+ . The SERRS (1×10-15 M) and SER(R)S (1×10-14 M) limits of detection of [Ru(bpy)3]2+ determined at 445 and 532 nm excitations, respectively, correspond to the single molecule level of the complex detection. Its achievement is attributed to a large electromagnetic mechanism enhancement experienced by [Ru(bpy)3]2+ incorporated in "hot spots", an efficient localization of "hot spots" in the 3D aggregate to the focus of the laser beam in micro-Raman spectral measurements and to a molecular resonance contribution to the...

APA, Harvard, Vancouver, ISO, and other styles

36

Pokorný, Martin. "Laserová spektroskopie polovodičových kvantových bodů." Master's thesis, 2012. http://www.nusl.cz/ntk/nusl-308180.

Full text

Abstract:

This work is focused on examining photoluminescent properties of InAs quantum dots (QDs) on GaAs substrate covered by GaAs1-xSbx strain reducing capping layer (SRL) prepared by Stranski-Krastanow method. We measured luminescence decay time of two samples with different concentration of Sb in this layer. We investigated the influence of temperature, intensity and wavelength of the excitation pulse on the luminescent decay time. We also compared the properties of the samples after excitation by 760 nm pulse and 850 nm pulse - the former one is energetically above the substrate band gap; in the second case we excited only the QDs and the wetting layer (WL). We consequently derived recombination and relaxation processes occurring inside InAs QDs and also the transport of charge carriers from the substrate and the WL into QDs. One part of this diploma thesis was to learn about the methods of measuring ultrafast photoluminescence and build the experimental set-up.

APA, Harvard, Vancouver, ISO, and other styles

37

Bhowmik, Sandip. "Design and Application of Bile-Salt/Lanthanide Based Hydrogels." Thesis, 2013. http://etd.iisc.ernet.in/2005/3300.

Full text

Abstract:

Chapter 1: Introduction to the luminescent properties of lanthanides Luminescence properties of trivalent lanthanides have been explored extensively over the past few decades owing to their unique properties. Lanthanides emission is known to be due to intra-configurational f-f transitions. Because the partially filled 4f shell is well shielded from its 26 environment by the closed 5sand 5pshells, the ligands in the first and second coordination sphere perturb the electronic configurations of the trivalent lanthanide ions only to a very limited extent. This leads to interesting properties such as long lifetimes, sharp line-like emissions etc. which in turn make lanthanides very attractive choice for commercial optical applications. Despite this, the scope of applications remained limited because of the low molar extinction coefficient values of the forbidden lanthanide f-f transitions. However, this problem has been successfully addressed by complexing the lanthanide ion with suitable ligands which can sensitize it resulting in a significant increase in the emission intensity (so called “antenna effect”). The strategy worked very well and resulted in widespread applications of lanthanides form biology to optoelectronics. This chapter discusses elementary ideas regarding the mechanism of sensitization and relevant examples that traces various applications of such lanthanide complexes from the current literature. Chapter 2: A self-assembled Europium Cholate hydrogel: a novel approach towards lanthanide sensitization Luminescent lanthanides can be of great value in a number of possible applications but their scope is limited by their intrinsic low molar absorptivities. Though this problem can be circumvented by complexing the lanthanide ion with suitable chelating ligands to improve the luminescence properties drastically, the design of such systems often involves meticulous planning and laborious synthetic steps to obtain a ligand suitable for the job. It is therefore desirable to have a simpler version of a sensitizing system that does not require the complexities of a chelating ligand but can sensitize trivalent lanthanides with comparable efficiency. It was observed in our group that divalent metal ions (Ni2+, Zn2+, Cu2+, Coetc.) form hydrogels on addition of sodium cholate. We extended to obtain hydrogels of trivalent lanthanides. Furthermore, when the gel was doped with pyrene, a ten-fold increase in the intensity of Eu(III) emission was observed (Fig 2). Thus we established a unique way to sensitize lanthanides in a hydrogel media by non-coordinating chromophores. The approach was completely modular in nature and avoids any laborious synthesis. We also tried other derivatives of pyrene as sensitizers and found that 1-pyreneboronic acid also caused similar sensitization of Eu(III). Fig 2. (a) Schematic representation of the sensitization process (the arrangement of molecules in the gel fiber is arbitrary). Eu-cholate (5 mM/15 mM) gel (a) normal light and (b) 354 nm UV excitation in the presence of 6 μM pyrene Further studies revealed, that 2,3-dihydroxynapthalene (DHN) can sensitize Tb(III) in a similar hydrogel. We also demonstrated Tb(III) to Eu(III) energy transfer process occurring in the gel when doped with DHN. This allowed us to achieve a hydrogel system with tunable luminescence properties (by varying relative ratios of Tb(III) and Eu(III) ). When the effect of divalent metal ions on such energy transfer processes were explored, it was observed that the luminescence from the composite gel of Tb(III)/ Eu(III) is tunable by Zn(II) and through proper manipulation of concentrations one can obtain white light emitting gel (Fig 3). Fig 3. Effect of Zn(II) (from left to right 0 mM, 2.8 mM, 11.3 mM) on Tb3+ (4.5 mM)/Eu3+ (0.11mM)/ sodium cholate (13.6 mM) gels. b) Tb/Eu/Zn-cholate gel (Tb3+ (4.4 mM), Eu3+ (0.11 mM), Zn2+ (7.4 mM), NaC (13.6 mM, DHN 0.2 mM) under 365 nm UV lamp (c) CIE 1931 diagram depicting the luminescence as white (black spot). Chapter 3. A “Pro-Sensitizer” based Sensing of Enzymes using Tb(III) Luminescence in a Hydrogel matrix This chapter descirbes design and realisation of a sensor system based on Tb(III) luminescnece for the detection of enzymes. The idea involved synthesizing a covalently modified DHN molecule by attaching appropriate enzyme cleavable units. We coined the term “pro-sensitizer”to describe the modified molecule which would not sensitize Tb(III) in the gel matrix but when proper enzymes are applied the free form of DHN would be released triggering a luminescence response from Tb(III). This would enable us to monitor the acitivities of the particular enzyme by examining the luminescence intensity enhancement with time (Fig 4) Fig 4. A “pro-sensitizer” based approach to detect different types of enzymes in a hydrogel matrix through Tb(III) luminescence. We applied the idea to develop a novel luminogenic gel probe for inexpensive and rapid detection of three different hydrolases, lipase, β–glucosidase and α-chymotrypsin. The corresponding “pro-sensitizer”for each enzyme were synthesized (Fig 5).The sensing technique depends on the gel matrix to provide the nessesary platform for lanthanide sensitization. Thereofore, it enjoys an edge over the contemporary techniques that typically involve specially designed and synthesized multidentate chelating ligands for this purpose. We also determined important kinetic parameters of all the enzymes, thus enabling us to have a better insight into the activity of the enzymes in the hydrogel matrix. Fig 4. Pro-sensitizers molecules for (1) lipase, (2) β-glucosidase and (3)α-chymotrypsin Chapter 4. A novel approach towards templated synthesis of lanthanide trifluoride nanoparticles Nanomaterials with excellent optical properties have been of special interest. Lanthanide derived nanoparticles, owing to their unique physical properties, provide an excellent choice for applications such as biolabels, lasers, optical amplifiers, and optical-display phosphors. Several types of lanthanide nanoparticles or nanocrystals are reported in the literature such as Nd2O3, Eu2O3, Gd2O3, Tb2O3, and Y2O3. Among them lanthanide fluoride nanoparticles have emerged as the best choice because of their low phonon energy, and thus minimum quenching of emissive Lnions thereby allowing maximum efficiency for several optical applications. In previous literature precedence, LnF3 nanoparticles were typically synthesized following conventional approaches which necessitate use of high temperatures, high pressures (hydrothermal techniques) and capping ligands. In this chapter, we demonstrated a simpler synthesis of LnF3 nanoparticles at ambient temperatures without the requirement of added capping agents. The room temperature synthesis of LnF3 was unprecedented and was achieved simply by diffusing NaF solution through the hydrogels of corresponding Ln-cholate gels. The nanoparticles were characterized by transmission electron microscopy (TEM) and by powder XRD analysis which established the presence of very small (3-4 nm) nanoparticles mono-dispersed uniformly over the the gel matrix (Fig 6). The LnF3 containing xerogels of Tb(III) and Eu(III) cholate gels were also shown to be highly emissive. Fig 6. HRTEM images of a) TbF3, b) GdF3, c) NdF3 and d) DyF3 in their corresponding gel media.

APA, Harvard, Vancouver, ISO, and other styles

38

Dzurňák, Branislav. "Studium polovodičů metodami časově rozlišené laserové spektroskopie: Luminiscenční spektroskopie nanokrystalického diamantu." Doctoral thesis, 2012. http://www.nusl.cz/ntk/nusl-307932.

Full text

Abstract:

Title: Study of semiconductors by methods of time resolved laser spectroscopy: Luminescence spectroscopy of nanocrystalline diamond Author: Branislav Dzurňák Department: Department of Chemical Physics and Optics Supervisor: doc. RNDr. František Trojánek, Ph.D. Abstract: The PhD thesis is focused on optical properties of nanocrystalline diamond prepared by chemical vapour deposition method. Photoluminescence of nanocrystalline diamond samples and effects of ambient temperature, pressure, pH and UV irradiation on it are studied by laser spectroscopy. Results suggest the keyrole of water and air adsorbates which affect the energy states in the sub-bandgap region of diamond. Photoluminescence decay of samples of different surface termination and structure and its dependency on ambient pressure and temperature is studied by methods of ultrafast (picosecond and nanosecond scale) laser spectroscopy. Results are analysed by power-law decay function which fits well the luminescence decay curves and also describes the dynamics of charge carriers in states localised within the bandgap. The model of interaction of nanocrystalline diamond with air adsorbates is proposed. Non-linear optical properties of nanocrystalline diamond are also studied, namely the generation of second and third harmonic frequency. The thesis...

APA, Harvard, Vancouver, ISO, and other styles

39

Žídek, Karel. "Nelineární optické vlastnosti křemíkových nanostruktur." Doctoral thesis, 2010. http://www.nusl.cz/ntk/nusl-296108.

Full text

Abstract:

Název práce: Nelineární optické vlastnosti křemíkových nanostruktur Autor: Karel Žídek Katedra (ústav): Katedra chemické fyziky a optiky Vedoucí disertační práce: Doc. RNDr. František Trojánek, Ph.D. E-mail vedoucího: trojanek@karlov.mff.cuni.cz Abstrakt: Disertační práce se zabývá nelineárními optickými jevy a ultrarychlým vývojem luminis- cence křemíkových nanokrystalů. Pomocí metody optického hradlování signálu (časové rozlišení až 250 fs) porovnáváme ultrarychlý vývoj luminiscence křemíkových nanokrystalů s různými ve- likostmi (v řádu jednotek nanometrů) a také s rozdílnými formami pasivace. Pro nanokrystaly, kde po excitaci dominuje vliv zachytávání nosičů do povrchových stavů nanokrystalu, navrhujeme teoretický popis závislosti rychlosti těchto procesů na vlastnostech nanokrystalů. Dále v práci podrobně zkoumáme působení Augerovy rekombinace, která se projevuje jak v časově rozlišené, tak i v časově integrované emisi vzorků. Experimentální data velmi dobře popisuje námi navržený model na bázi kinetických rovnic. Závěr práce se zaměřuje na zkoumání ultrarychle dohasínající stimulované emise. U stávajících metod měření optického zisku (VSL a SES) navrhujeme jejich rozšíření pro...

APA, Harvard, Vancouver, ISO, and other styles

40

Hynek, Jan. "Příprava a vlastnosti nanodestiček hydroxidu zinečnatého a oxidu zinečnatého." Master's thesis, 2014. http://www.nusl.cz/ntk/nusl-338742.

Full text

Abstract:

1 Abstract The structure of layered zinc hydroxide intercalated with dodecyl sulfate (LZH-DS) anions was studied in detail. LZH-DS was prepared by direct precipitation in water and formed different phases. The following phases of LZH-DS were prepared - "extended" phase (ex) by direct precipitation in water, "shrunk" (s) and "super-shrunk" (ss) phases via treatment of LZH-DS(ex) phase in methanol. The studies of the thermal behavior of LZH-DS(ex) revealed interstratification of intercalated DS anions. It is the first example of interstratification in layered hydroxides that are intercalated with long aliphatic alkyl chain anions. The experimental results were used for molecular dynamic modelling of the structures. Nanometric thin films were prepared by dip-coating and inkjet printing of ZnO nanosheets on glass plates. The side-by-side alignment of the ZnO nanosheets on the substrate resulted in thin, transparent, oriented ZnO surfaces with the high-energy {001} facets exposed. The method of nanosheet deposition affected the film morphology; the dip-coated films were smooth and nonporous, while the inkjet-printed films were rough and had a surface area in the range of approximately 100-160 m2 g-1 . The first-order rate constants for the photocatalytic degradation of 4-chlorophenol on the nanosheet-based films...

APA, Harvard, Vancouver, ISO, and other styles

41

Pánik, Róbert. "Určení geologické provenience katodoluminiscenční spektroskopií apatitů a karbonátů." Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-335190.

Full text

Abstract:

This work presents new method for determination of geological provenance based on the statistical analysis of cathodoluminescence spectra of marbles and carbonate rocks from various localities in the Bohemian Massif. Analysis is based on the combination of data from seven different measures of spectral similarity and provides results that are more robust than those obtained by approach based only on a single measure of similarity. These results may be further improved by employing meta-analysis that evaluates behaviour of spectra during the individual steps of analysis. Analysis was performed on the original cathodoluminescence spectra, as well as on the residual spectra in which relative variability was amplified by the subtraction of Gaussian trend present in all spectra of carbonates. By combining results from analysis and meta-analysis of both original and residual spectra it was possible to almost unambiguously determine provenance of samples from all studied localities. Agglomerative hierarchical clustering was employed as a supplementary method for classification of spectra. Out of 72 different methods for clustering, one was selected for both original and residual data based on the number of correctly classified spectra. Second part of this work presents analysis of cathodoluminescence...

APA, Harvard, Vancouver, ISO, and other styles

42

Procházka, Jan. "Fotoluminiscence krystalů CdTe." Doctoral thesis, 2013. http://www.nusl.cz/ntk/nusl-328694.

Full text

Abstract:

Title: Photoluminescence of CdTe crystals Author: Jan Procházka Department: Institute of Physics of Charles University in Prague Supervisor: Doc. RNDr. Pavel Hlídek, CSc. Abstract: Energy levels connected with defects in nominally undoped crystals CdTe, indium- doped crystals and chlorine-doped crystals were studied using low-temperature photoluminescence. The crystals are intended for X- and gamma- ray detectors operated at room temperature. An effect of annealing in cadmium or tellurium vapor on luminescence spectra was investigated. Some changes were interpreted by filling of vacancies not only by atoms coming from gaseous phase but also by impurities from defects like interstitials, precipitates, inclusions, grain boundaries etc. The luminescence bands assigned to defects important for compensation mechanism were examined, namely A-centers (complexes of vacancy in cadmium sublattice and impurity shallow donor) and complexes of two donors bound to a vacancy. It was shown, that temperature dependence of the luminescence bands results from more complicated processes than a simple thermal escape of bound excitons or thermal excitation of electrons (holes) from defects to bands. We observed expressive "selective pair luminescence" bands (SPL) on partially compensated In-doped samples during sub-gap...

APA, Harvard, Vancouver, ISO, and other styles

43

Horký, Filip. "Měďné komplexy s fosfinonitrilovými donory." Master's thesis, 2017. http://www.nusl.cz/ntk/nusl-356099.

Full text

Abstract:

Title: Copper(I) complexes with phosphinonitrile donors Author: Bc. Filip Horký Department: Department of Inorganic chemistry Supervisor: prof. RNDr. Petr Štěpnička, Ph.D. Abstract: Although coordination compounds with phosphinonitrile ligands are already well known, in the vast majority of these complexes these ligands coordinate as simple P-donors with their cyano groups acting as auxiliary substituents. This led us to synthesize and study a series of Cu(I) complexes with two isomeric phosphinonitrile donors, namely 2-(diphenylphosphino)benzonitrile (Lo ) and 2-(diphenylphosphino)benzonitrile (Lp ), with different ligand-to-metal ratios and possibly characterize further coordination modes offered by these hybrid donors. This work describes the preparation of phosphinonitrile complexes from the aforementioned ligands and simple copper(I) halides (CuX, X = Cl, Br, I), pseudohalides (X = CN) and from [Cu(MeCN)4][BF4]. The products were characterized by nuclear magnetic resonance, infrared spectroscopy and elemental analysis, mass spectrometry, and their solid-state structures were determined by single-crystal X-ray crystallography. In addition, luminescent properties of the Cu(I) complexes were studied and catalytic activity of selected complexes was tested in copper-catalyzed alkyne-azide cycloaddition...

APA, Harvard, Vancouver, ISO, and other styles

44

Fučíková, Anna. "Bioaplikace nových nanostrukturních materiálů." Doctoral thesis, 2012. http://www.nusl.cz/ntk/nusl-312192.

Full text

Abstract:

Title: Bioapplications of novel nanostructured materials Author: Anna Fučíková Department / Institute: Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University in Prague Supervisor of the doctoral thesis: Doc. RNDr. Jan Valenta, Ph.D., Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University in Prague Abstract: This work is aimed at development of new fluorescent labels based on silicon nanocrystals. Nanodiamonds and commercial CdSe quantum dots have been used as comparative materials. Silicon nanocrystals are relatively small (1-4 nm) compared to other studied nanomaterials. They are prepared by electro-chemical etching and their surface can be activated by various molecules which strongly influences luminescence properties. Luminescence quantum efficiency can be as high as 30 % and perfectly photostable even in biological environment. Si nanocrystals are biodegradable in a living organism within reasonable time scale and non-toxic. We are able to detect luminescence of single nanocrystals, even inside living cells, with use of our micro-spectroscopy apparatus. Nanodiamonds have weak luminescence; they are toxic at higher dosages and very stable in living bodies (without available technique how to remove them). Studied CdSe...

APA, Harvard, Vancouver, ISO, and other styles

45

Vašková, Lucie. "Studium vlivu IgY na interakce bakterií a plicních buněk v podmínkách ex vivo." Master's thesis, 2016. http://www.nusl.cz/ntk/nusl-344105.

Full text

Abstract:

0 Abstract Cystic fibrosis is an autosomal recessive disease caused by mutation in CFTR gene coding for a chloride channel in apical membrane of epithelial cells. This disorder leads to the change in ion transport causing the increase in mucus viscosity in airways as well as changes in glycosylation of saccharide structures on the cells. Because of that these cells are the target for bacterial adhesion. Chronic bacterial infections, which lead to gradual decline of lung function and damage of lung tissue, are the major cause of death of patients suffering with cystic fibrosis. Pseudomonas aeruginosa is the main pathogen causing chronic infections in cystic fibrosis patients. This bacterium produces a biofilm protecting them from host immune system and antibiotics. Once the colonization with PA occurs, it is difficult to get rid of this pathogen. The prophylactic treatment with orally administered hen antibodies against the PA virulence structures could be a prevention of chronic PA infections. In this work we tested the antibody against the bacterial lectin PA-IIL, which is suggested to be involved in the adhesion of the pathogen on epithelial cells. First, it was verified that the prepared antibody from egg yolks of a hen immunized with the bacterial lectin PA-IIL recognizes this antigen expressed...

APA, Harvard, Vancouver, ISO, and other styles

46

Chlouba, Tomáš. "Studium optických nelinearit v polovodičích a polovodičových nanostrukturách." Doctoral thesis, 2019. http://www.nusl.cz/ntk/nusl-410180.

Full text

Abstract:

In the main part of this thesis I study the relaxation mechanisms of charge carriers in silicon nanocrystals in SiO2 matrix. One of the potential applications of these structures lies in photovoltaics, specifically in construction of all-silicon tandem solar cells. I studied the dynamics of carriers in these structures by methods of ultrafast spectroscopy which helped to unravel the microscopic behaviour of carriers, their transport, localization etc. Furthermore I investigated the doping of such structures as the technology of doping is crucial for manufacture of pn- junctions which are the core component of solar cells. At the end I delve into the dissipative Jaynes-Cummings model by mathematical modeling and theoretical calculations which describes among others microlasers and as such comes under a field of cavity quantum electrodynamics.

APA, Harvard, Vancouver, ISO, and other styles

47

Gajdošová, Veronika. "Nové přístupy k uspořádávání plasmonických nanočástic do 2D a 3D hybridních aktivních systémů pro SERS grafenu a SERS, SERRS a SERS + GERS aromatických molekul." Doctoral thesis, 2019. http://www.nusl.cz/ntk/nusl-405168.

Full text

Abstract:

In the first part of the Thesis, a new type of active system for SERS and SERRS of hydrophobic molecules, namely a 3-dimensional (3D) nanosponge aggregate with incorporated hydrophobic molecules has been developed, and tested by fullerene C60 and hydrophobic free- base tetraphenylporfine (H2TPP). The SERS and SERRS (surface enhanced /resonance/ Raman scattering) limits of detection (LODs) of C60 at four excitation wavelengths spanning the visible spectral region were found to be by one order of magnitude lower than in the reference system, which mimics the previously reported ways of utilization of Ag nanosponges as substrates for SERS and SERRS. The superiority of the newly developed sample is attributed to the efficient localization of the hydrophobic molecules into hot spots in 2D fractal aggregates of Ag nanoparticles (NPs). Diprotonation of H2TPP during the procedure using HCl as the preaggregation agent has been eliminated by employment of NaCl. On the other hand, investigation of the mechanism of H2TPP protonation during the former preparation procedure opened a possibility to employ Ag nanosponge aggregate as nanoreactor. In the second part of the Thesis, 2D assemblies of AgNPs were found to be better substrates for SERS of single layer graphene (SLG) than the 3D ones. In particular, the 2D...

APA, Harvard, Vancouver, ISO, and other styles

48

Štor, Tomáš. "Paleogeografický vývoj kenozoických říčních systémů ve středních a severních Čechách a jejich vztah ke klimatickým změnám a neotektonice." Doctoral thesis, 2018. http://www.nusl.cz/ntk/nusl-391377.

Full text

Abstract:

The main aim of this thesis is to provide greater details on the timing of the fluvial river systems formation in the middle and the northern Bohemia. We focused on the Ploučnice River and Vltava River evolution. The river systems are very complex therefore we have used multiple approaches of the research with the disciplines range from geology, sedimentology, geomorphology, geochemistry, over different dating methods such as 10Be and 26Al isochron burial dating, optically stimulated luminescence dating and radiocarbon dating methods. Our results suggests that the terraces are significantly older than previously proposed. The fluvial style of the Ploučnice River system changes from high-energy braided to long-bend meandered river in the upper terrace levels (36 to 29 m above the modern river) and from high- to medium-energy braided river in the middle terrace levels (22-14 m). In the lower terrace levels (13 to 5 m) high-energy braided to long-bend meandered river environments were identified. Terraces were dating at 34 m, 29 m and 14 m above the modern floodplain with cosmogenic radionuclides while the 19 m, 12 m and 6 m above the modern floodplain terraces were dating with OSL. The time span represented by the river terraces remains unclear and varies from Eburonian to Eemian (1.68 to 0.056 Ma)....

APA, Harvard, Vancouver, ISO, and other styles

49

Heydová, Radka. "Teoretická studie vlivu spin-orbitální interakce na spektra a fotofyziku rheniových komplexů." Doctoral thesis, 2017. http://www.nusl.cz/ntk/nusl-369436.

Full text

Abstract:

Title: Theoretical study of spin-orbit coupling on spectra and photophysics of rhenium complexes Author: RNDr. Radka Heydová Department: Physical and Macromolecular Chemistry Supervisor: Ing. Stanislav Záliš, CSc., JHI AS CR, v.v.i. Supervisor's e-mail address: stanislav.zalis@jh.inst-cas.cz Abstract: Relativistic effects, especially spin-orbit coupling (SOC), play an essential role in transition metal chemistry and SOC treatment is indispensable for a correct theoretical description. To demonstrate the importance of SOC, the energies and oscillator strengths of vertical transitions for a series of [ReX(CO)3(2,2'-bipyridine)] (X = Cl, Br, I) and [Re(imidazole)(CO)3(1,10-phenanthroline)]+ complexes were calculated in the spin-free (SF) and spin-orbit (SO) conceptual frameworks. Two different computational approaches were adopted: SO-MS-CASPT2 where SOC was added a posteriori using a configuration interaction model (SO-RASSI), and the approximate perturbative SO-TD-DFT method. Relativistic effects were included via the two-component Douglas-Kroll-Hess transformation and the zeroth-order regular approximation in the former and the latter technique, respectively. The SF (i.e. accounting only for the scalar relativistic effects) and SO results from both methods were compared with each other and to available...

APA, Harvard, Vancouver, ISO, and other styles

50

Konečný, Martin. "Mezioborové vztahy fyziky a chemie v přírodovědném vzdělávání." Master's thesis, 2016. http://www.nusl.cz/ntk/nusl-349187.

Full text

Abstract:

Title: Interdisciplinary relations of physics and chemistry in science education Abstract: This master's degree thesis deals with the topic of interdisciplinary relations of chemistry and physics in science education. According to the review, to conveniently integrate physics and chemistry the appropriate topics and approaches were selected. The thesis includes teaching materials and worksheets to the three topics (Evolution of the Universe and the Origin of Elements, Luminescence and Composition and Properties of Matter) that are suitable for integration of physics and chemistry. The teaching material "Evolution of the Universe and the Origin of the Elements" includes a study text for teachers and a shorter study text for pupils. The teaching material "Luminescence" is based on an independent research done by pupils with their own crafted UV-lamp, completed with the facts included in a powerpoint presentation. The teaching material "Composition and Properties of Matter" consists of three parts (The paraffin, The Candle and The Properties of Selected Organic Substances) and is designed for an independent research done by pupils. Listed study materials were checked by teachers during meetings and seminars. The thesis also includes an evaluation of listed study materials by an expert group of high school...

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Luminiscencia'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles