Dissertations / Theses: 'CdSe nanoparticle'

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Hill, Lawrence J. "Synthesis and Dipolar Assembly of Cobalt-Tipped CdSe@CdS Nanorods." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/332684.

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This dissertation contains four chapters with advances relevant to the fields of nanoparticle synthesis and nanoparticle self-assembly: a review of nanoparticle self-assembly, or “colloidal polymers”; dumbbell heterostructured nanorod synthesis; dipolar matchstick heterostructured nanorod synthesis; and self-assembly of dipolar matchsticks to form colloidal polymers. These chapters are followed by appendices containing supporting data for chapters two through four. The first chapter is a review summarizing current research involving the 1-D assembly of nanocrystals to form “colloidal polymers.” One of the major goals of materials chemistry is to synthesize hierarchical materials with precise controlled particle ordering covering all length scales of interest (termed, the “bottom up” approach). Recent advances in the synthesis of inorganic colloids have enabled the construction of complex morphologies for particles in the range of 1 – 100 nm. The next level of structural order is to control the structure of assemblies formed from these materials. Linear nanoparticle assemblies are particularly challenging to achieve due to the need to impart functionality to colloids such that (typically) only two sites are active per particle. An emerging idea in the literature which addresses this challenge is to consider linear assemblies of inorganic nanoparticles as colloidal analogs to traditional polymers. This conceptual framework has enabled the formation of linear assemblies having controlled composition (to form segmented and statistical copolymers), architecture (linear, branched, cyclic), and degree of polymerization (chain length). However, this emerging field of synthesizing colloidal polymers has not yet been reviewed in terms of methods to control fundamental polymer parameters. Therefore, linear nanoparticle assembly is reviewed in chapter 1 by applying concepts from traditional polymer science to nanoparticle assembly. The emphasis of chapter 1 is on controlling degree of polymerization, architecture, and composition for colloidal polymers, and seminal examples are highlighted which control these parameters. The second chapter is centered on a novel methodology to install ferromagnetic cobalt domains onto core@shell, “CdSe@CdS” nanorods. While the structures synthesized in this work were novel, the key advance from this work was the development of a methodology to separate nanorod activation from deposition of ferromagnetic cobalt domains onto semiconductor nanorods. As synthesized CdSe@CdS nanorods are passivated with strongly binding phosphonic acid ligands, and these ligands prevent direct deposition of many materials (such as cobalt). Synthetic methods must therefore modify nanorod surfaces prior to deposition of additional nanoparticle domains (tips). Previous synthetic methods for the deposition of magnetic domains onto nanorod termini typically combined activation of nanorod termini and metal deposition into a single synthetic step. While these previous reports were successful in achieving tipped nanorods, the coupling of these two reactions required matching the kinetics of nanorod activation and decomposition/reduction of metal precursors in order to achieve the desired heterostructure morphology. However, the presence of ligands used for nanorod activation can also affect the rate of metal precursor decomposition/reduction and the propensity of the metal to form free nanoparticles through homogeneous nucleation. Thus, simultaneous nanorod activation and metal deposition hinders modification of these syntheses to obtain differing heterostructured morphologies. In the work presented in chapter 2, we chemically activate nanorod termini towards cobalt deposition in a separate chemical step from deposition of metallic cobalt nanoparticle domains. First, reductive platinum deposition conditions were utilized to activate nanorod termini towards the deposition of cobalt domains, which were deposited in a subsequent reaction step. Then, the kinetics of nanorod activation during platinum deposition were tracked, and the platinum-tipped nanorod morphologies were correlated with the results of subsequent cobalt deposition reactions. Ultimately, controlled placement of cobalt domains onto one or both nanorod termini was demonstrated based on the degree of activation during platinum deposition. Cobalt nanoparticle tips were then selectively oxidized to form CoₓOy-tipped nanorods, which were a novel class of p-n type nanomaterials achieved over a total of five synthetic steps. Relevant supporting details for the synthesis of these dumbbell tipped nanorods are provided in Appendix A. The third chapter describes the synthesis of CoNP-tipped nanorods with a single, strongly dipolar, ferromagnetic CoNP-tip per nanorod. The key synthetic advance was the ability to activate a single terminus per nanorod without activation of lateral nanorod facets, which was vital in achieving these larger, dipolar, cobalt tips (rather than lateral decoration of cobalt onto nanorod lateral facets). These dipolar “matchstick” CoNP-tipped nanorods then spontaneously formed linear assemblies carrying nanorod side chains as pendant functionality. Activation of CdSe@CdS nanorods was found to occur through the deposition of small (< 2 nm) PtNP-tips which were not readily observable by standard characterization techniques. The finding that small (< 2 nm) PtNP-tips altered nanorod reactivity towards cobalt deposition emphasized the effect of subtle changes to nanorod surface chemistry. Relevant supporting details for the synthesis of these dipolar matchstick tipped nanorods are provided in appendix B. The fourth chapter is centered on the self-assembly of dipolar matchstick cobalt-tipped nanorods to form colloidal (co)polymers reminiscent of traditional bottlebrush polymers, with controlled composition and phase behavior on carbon surfaces. Similar to earlier findings in traditional polymer science, nanorod side chain length was found to significantly impact surface assembly of these colloidal analogs of bottlebrush copolymers, which provided a useful parameter for affecting surface wetting and phase behavior of nanoparticle thin films. This work was also the first demonstration of colloidal copolymers from the dipolar assembly of magnetic nanoparticles, where both segmented and statistical copolymer compositions were achieved. We then demonstrated, for the first time, that a colloidal copolymer with segmented composition can form a mesoscopic phase separated morphology which is similar to that observed for traditional block copolymers. This key advance opens the possibility of controlling structural ordering over still longer length scales by the development of methods to control phase separated morphologies in a manner similar to traditional block copolymers. Relevant supporting details for the synthesis and assembly of these colloidal bottlebrush polymers are provided in appendix C.

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Doherty, Rachel Pamela. "Preparation and characterisation of CdSe quantum dots : a nanoparticle photoelectrode." Thesis, University of Bristol, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.432974.

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Antonello, Alessandro. "MULTIFUNCTIONAL NANOSTRUCTURED MATERIALS BASED ON CdSe AND TiO2 NANOPARTICLES." Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3421896.

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Nanotechnology has arisen as one of the most important fields in recent research, for the implications in both basic and applied science and technological applications. The manipulation of matter at the nanoscale is accompanied by the appearance of novel properties and large surface to volume ratio which can be exploited in a number of applications ranging from optics, catalysis and sensing, to name a few. In this work, we mainly focused on the synthesis and the use of nanomaterials for the preparation of nanocomposites and structures to be employed in the optical field. The main advantage of introducing nanosized inclusions in a host material is that specific functionalities or desired optical change can be imparted while transparency in the visible range can be retained. The whole activity can be divided in the synthesis and processing of nanoparticles and in their usage for some specific application. Cadmium selenide (CdSe), Titanium dioxide and layered titanates have been mainly addressed due to PL emission properties and high refractive index. In addition, zinc sulfide (ZnS) nanoparticles have been synthesized. CdSe nanoparticles (Quantum Dots) have been obtained by colloidal chemistry and part of the work has been spent in the synthesis of core-shell nanoparticles with a CdSe core and a shell of semiconductor materials with wider band gap in order to increase the stability of the emission properties of such materials. These nanoparticles were introduced in sol-gel derived ZrO2 waveguides to obtain materials showing optical gain which was characterized by ASE (Amplified Spontaneous Emission) experiments. High refractive index materials are useful in many optical applications. High refractive index depositions were obtained introducing Titania nanoparticles in proper matrices. A sol-gel synthesis for titanium dioxide nanoparticles has been developed yielding to anatase particles in the 3-5 nm range. These were embedded in an epoxy-based hybrid material obtaining transparent depositions with refractive index in the 1.51-1.89 range. Layered titanates were further addressed since they allowed extending the processing and engineering of titanium oxide materials. A synthetic colloidal procedure was developed, in which titanate nano-sheets are produced by reaction of a titanium alkoxide and an organic base. These materials allowed to obtained composites with multifumctional properties since materials embedding both titanate sheets and quantum dots could be obtained and applied in PL active waveguide and functional coating for LED devices to improve light extraction and produce white light through down-conversion. Coatings for LED were also developed using conventional sol-gel derived hybrid materials. The obtained layered titanates could also be modified and treated by UV curing, leading to material’s densification and enhancement of the refractive index at relatively low temperatures (200 °C). This processing behavior has been exploited in Bragg mirror fabrication and vertical optical microcavity incorporating quantum dots. The procedure employed for microcavity fabrication was found to be effective in keeping the optical properties of quantum dots, allowing for optical characterization of this structure. The properties of titanium dioxide have been exploited for optical gas sensing applications embedding gold nanoparticles in a crystalline TiO2 matrix. Anatase TiO2 particles have been successfully used as matrix material for this application. The employed preparation of such nanocomposites allowed tailoring of porosity and gold-titania interface which could be studied by optical measurements. Optical sensing was evidenced by variation in thin film absorbance at wavelengths near the plasmon resonance of gold nanoparticles caused by the presence of the gas analytes. Gold nanorods were introduced in the synthesized titanates. Gold nanorods are known to spheroidise upon thermal treatment, losing their peculiar optical properties. We found that the processing treatments developed for titanates resulted in improved thermal stability of such nanostructures as shown by optical measurements. This result is very interesting since it would allow extending gold nanorods’s exploitation in optical applications. Finally, composites with enhanced refractive index were realized by introducing ZnS nanoparticles in hybrid sol-gel material. A synthesis of ZnS nanoparticles has been developed, which allows nanoparticles functionalization and introduction in a hybrid organic-inorganic sol-gel matrix.
Il campo delle nanotecnologie è diventato tra i più importanti nella recente ricerca scientifica. È’ un settore multidisciplinare nelle conoscenze che ne costituiscono le basi e trova applicazione in svariati ambiti della tecnologia. La manipolazione della materia su nanometrica è accompagnata dalla comparsa di nuove proprietà ed un elevato valore di superficie per unità di volume. Queste proprietà possono essere sfruttate in applicazioni nei campi dell’ottica, della catalisi e della sensoristica, per non citarne che alcuni. In questo lavoro, l’attività è stata principalmente focalizzata sulla sintesi e l’uso di materiali nanostrutturati per la preparazione di nanocompositi e strutture di interesse nel campo dell’ottica. Il vantaggio principale nell’ introdurre particelle nanometriche in un materiale risiede nella possibilità di introdurre specifiche funzionalità o variazioni nelle proprietà ottiche mantenendo nello stesso tempo la trasparenza nel visibile. L’intera attività può essere divisa nella sintesi e successiva manipolazione di nanoparticelle e nel loro uso in specifiche applicazioni. Seleniuro di Cadmio (CdSe), Biossido di Titanio (TiO2) e Titanati a strati sono stati principalmente presi in considerazione per sfruttare specifiche proprietà di fotoluminescenza e di elevato indice di rifrazione. Sono inoltre state sintetizzate nanoparticelle di Solfuro di Zinco (ZnS). Nanoparticelle di CdSe, anche chiamate Quantum Dots (QDs), sono state ottenute attraverso sintesi di tipo colloidale. Parte del lavoro è stata dedicata al ricoprimento di queste nanoparticelle con semiconduttori a più elevato band gap con lo scopo di aumentare la stabilità delle proprietà di emissione di questi materiali. Queste nanoparticelle sono state introdotte in guide d’onda costituite da Biossido di Zirconio (ZrO2) ottenuto per via sol-gel per ottenere materiali con proprietà di guadagno ottico testate in esperimenti di emissione spontanea amplificata (ASE). Materiali ad alto indice di rifrazione trovano utilizzo in molte applicazioni ottiche. Deposizioni a elevato indice di rifrazione sono state ottenute introducendo particelle di biossido di titanio in opportune matrici. E’ stata sviluppata una sintesi di tipo sol-gel in grado di produrre soluzioni colloidali stabili di particelle cristalline con la struttura cristallografica dell’anatase con diametro intorno a 3-5 nm. Queste nanoparticelle sono state introdotte in una matrice ibrida sol-gel ottenendo deposizioni trasparenti con indice di rifrazione variabile tra 1.51 e 1.89. Sono stati successivamente presi in considerazione i titanati a strati perché permettono di estendere le possibilità di manipolazione ed ingegnerizzazione di materiali a base di ossido di titanio. È stata sviluppata una sintesi colloidale in cui “foglietti“ nanometrici di titanati sono prodotti per reazione di un alcossido di titanio e una base organica. Questi materiali hanno permesso di ottenere compositi con proprietà multifunzionali. Infatti, materiali contenenti titanati lamellari e QDs sono stati ottenuti e applicati in guide d’onda con proprietà di fotoluminescenza e ricoprimenti funzionali su dispositivi LED per migliorare la frazione di luce estratta e produrre luce bianca per conversione di parte della luce emessa in luce a lunghezza d’onda maggiore. Ricoprimenti per LED sono inoltre stati sviluppati con materiali ibridi sol-gel più convenzionali. I titanati stratificati sono stati trattati utilizzando radiazione UV. Questo genere di trattamento porta a una densificazione del materiale con conseguente aumento dell’indice di rifrazione impiegando durante il processo temperature relativamente basse (200 °C). Questo trattamento è stato impiegato nella fabbricazione di specchi multistrato dielettrici e cavità ottiche verticali dove sono stati inseriti QDs come emettitori luminescenti. Il metodo utilizzato è stato verificato essere compatibile con la conservazione delle proprietà di emissione dei Quantum Dots, permettendo la caratterizzazione ottica delle strutture sviluppate. Sono state inoltre considerate applicazioni sensoristiche per il rilevamento di gas tramite misure ottiche di materiali a base di TiO2 contenenti nanoparticelle d’oro. Le nanoparticelle di anatase in precedenza menzionate sono state adoperate come matrice, consentendo sia di agire sulla porosità, sia di caratterizzare l’interfaccia oro/titania tramite misure ottiche. La funzionalità sensoristica è stata determinata studiando la variazione nell’assorbanza ottica a lunghezze d’onda vicine alla risonanza plasmonica delle particelle d’oro, causata dalla presenza di uno specifico gas nell’atmosfera. Nanorods di oro sono stati inseriti in matrici di titanati lamellari. Queste nanostrutture d’oro tendono ad assumere la forma sferica in seguito a trattamento termico perdendo così le loro specifiche proprietà. Il trattamento di densificazione sviluppato per i titanati è stato applicato per questi compositi, fornendo una migliore stabilità termica dei nanorods, come dimostrato da misure ottiche. Questo risultato è interessante poiché potrebbe permettere di estendere l’utilizzo di queste nanostrutture in applicazioni ottiche. Infine, sono stati realizzati compositi con aumentato indice di rifrazione utilizzando particelle di solfuro di zinco per le quali è stata sviluppata una sintesi colloidale e una procedura di funzionalizzazione per il loro inserimento in matrici ibride sol-gel.

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Yaacob, Khatijah Aisha. "Formation and characterisation of CdSe-TiO2 nanoparticle films by electrophoretic deposition." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/6917.

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Electrophoretic deposition (EPD) was used to form a composite layer of mercaptoundeconic acid (MUA) capped CdSe-TiO2 nanoparticle on a fluorine doped indium tin oxide (FTO) substrate. The CdSe-TiO2 layer can be employed to fabricate a quantum dot sensitized solar cells (QDSSC), increased contact between CdSe and TiO2 nanoparticles and leading to improved efficiency of the solar cells. A colloidal suspension of TOPO capped CdSe nanoparticles was prepared by the hot injection method, followed with ligand exchange in order to produce MUA capped CdSe nanoparticles. CdSe particle of diameter in the range of 2.44 nm to 3.26 nm were to be used in this research. The TiO2 nanoparticles were prepared by hydrolysis of titanium isopropoxide in water and produced particles size of 4.66 nm. Both nanoparticles were suspended in ethanolic medium. Electrophoretic deposition parameters were optimized. The results show that an applied voltage of 5 V, was suitable to be used to deposit single layer of MUA capped CdSe, TiO2 nanoparticles and the mixture of MUA capped CdSe-TiO2 nanoparticles. Smooth, uniform and dense layer were produced under this applied voltage. EPD also allows deposition of multilayer structures, in this research two layer structures of MUA capped CdSe on electrophoretically deposited TiO2 on FTO and mixed MUA capped CdSe-TiO2 on electrophoretically deposited TiO2 on FTO were formed. Three layer structures of MUA capped CdSe/MUA capped CdSe-TiO2/ TiO2/FTO were also synthesised. The photocurrent was measured on single layer, two layer and three layers electrodes. The optimum photocurrent parameters for each single layer were studied, in order to measure the photocurrent at the best condition possible. The highest IPCE value recorder was 0.70 % on MUA capped CdSe on FTO, with the MUA capped CdSe size of 2.94 nm. The lowest IPCE, 0.011 %, was obtained from three layer structure of MUA capped CdSe/MUA capped CdSe-TiO2/ TiO2/FTO.

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Bair, Nathan A. "Synthesis and Characterization of an Oligothiophene-Ruthenium Complex and Synthesis and Optical Properties of Oligothiophene-Ruthenium Complexes Bound to CdSe Nanoparticles." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2596.

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Oligothiophenes are of increasing interest in organic based electronic devices in part due to their high electron and hole mobilities. In an organic photovoltaic (OPV) device, the electronic properties of oligothiophenes make them advantageous as charge transfer junctions. To serve as charge transfer junctions, oligothiophenes must be functionalized to bind to the donor and acceptor parts of the device. The donor and acceptor parts are different materials and the synthesis of asymmetric oligothiophenes is of great interest. Previous researchers in our lab synthesized four asymmetric oligothiophenes, two with two thiophene subunits and two with four. Each set of oligothiophenes contained a pair of constitutional isomers. Here we report the synthesis of another asymmetric oligothiophene, one with three thiophene subunits. This compound is functionalized with bipyridine to bind Ru(bpy)22+ and with phosphonic acid moieties to bind CdSe nanoparticles. The synthesis was carried out by bonding a phosphonic acid moiety to bithiophene and bipyridine to thiophene and then coupling the phosphate-bithiophene and thiophene-bipyridine. Standard Stille couplings were used for carbon-carbon bond formation. The resulting compounds have complex NMR spectra and overlapping Ru MLCT and π-π* transitions at 450 nm with molar extinction coefficient on the order of 3 x 105 M-1 cm-1. The thiophene fluorescence is quenched by Ru(bpy)22+. These optical properties compare closely with the previous compounds synthesized. Solar cells occupy significant attention in the media, politics and science for their promise of continual pollution-free energy. Quantum dots, metal complexes and organic compounds are all under research as viable replacements for expensive silicon solar cells. To test the efficacy of a light harvesting compound before constructing a solar cell, a model system is constructed to show electron transfer from the light harvester into an electron acceptor. We synthesized oligothiophenes and oligothiophene-ruthenium complexes and tested their ability to act as sensitizers and charge transfer junctions. To do this, they were bonded to CdSe nanoparticles and their optical properties were measured. Steady-state photoluminescence and time correlated single photon counting were used to observe the effects on fluorescence and fluorescence lifetime of the CdSe-oligothiophene and CdSe-oligothiophene-ruthenium complexes before and after binding. It was found that CdSe fluorescence was quenched when bound to an oligothiophene ruthenium complex, and that the fluorescence of the oligothiophene was quenched when bound to CdSe in the absence of ruthenium. The fluorescence lifetimes of the quenched species were shortened.

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Dickerson, Bryan Douglas. "Organometallic Synthesis Kinetics of CdSe Quantum Dots." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/27322.

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CdSe quantum dots produced by organometallic synthesis are useful as tunable emitters for photonic devices and as multi-colored protein markers for biomedical imaging, applications requiring bright and narrow emission. A diffusion-limited model helped monitor growth rates via photoluminescence and absorbance spectroscopy, in order to characterize synthesis kinetics in stearic acid, dodecylamine, and in trioctylphosphine oxide. The nucleation rate increased with Se concentration, while the growth rate followed the Cd concentration. Emission peak widths, emission redshift rates, nanocrystal growth rates, and reactant concentrations all decreased to a minimum when emission reached the critical wavelength, at a reaction completion time, tc. The temperature dependence of 1/tc and of redshift rates followed Arrhenius behavior governed by activation energies, which were tailored by the choice of solvent. Synthesis in solvents, such as stearic acid, with lower activation energies produced faster initial nanocrystal growth and longer critical wavelengths. The highest photoluminescence quantum yield was generally at wavelengths shorter than the critical wavelength, when moderate growth rates enabled surface reconstruction while precursors were still available.
Ph. D.

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Herz, Erik. "Colloidal Semiconductor Nanocrystals: A Study of the Syntheses of and Capping Structures for CdSe." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/10147.

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Luminescent quantum dots (QDs) or rods are semiconductor nano-particles that may be used for a wide array of applications such as in electro-optical devices, spectral bar coding, tagging and light filtering. In the case under investigation, the nano-particles are cadmium-selenide (CdSe), though they can be made from cadmium-sulfide, cadmium-telluride or a number of other II-VI and III-V material combinations. The CdSe quantum dots emit visible light at a repeatable wavelength when excited by an ultraviolet source. The synthesis of colloidal quantum dot nanoparticles is usually an organo-metallic precursor, high temperature, solvent based, airless chemical procedure that begins with the raw materials CdO, a high boiling point ligand, and a Se-trioctylphosphine conjugate. This investigation explores the means to produce quantum dots by this method and to activate the surface or modify the reaction chemistry with such molecules as trioctylphosphine oxide, stearic acid, dodecylamine, phenyl sulfone, aminophenyl sulfone, 4,4'dichlorodiphenyl sulfone, 4,4'difluorodiphenyl sulfone, sulfanilamide and zinc sulfide during the production to allow for further applications of quantum dots involving new chemistries of the outer surface. Overall, the project has been an interesting and successful one, producing a piece of equipment, a lot of ideas, and many dots with varied capping structures that have been purified, characterized, and stored in such a way that they are ready for immediate use in future projects.
Master of Science

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Vannoy, Charles Harvey. "Behavioral Effects of Functionalized CdSe/ZnS Quantum Dots in Self-Organization and Protein Fibrillation." Scholarly Repository, 2010. http://scholarlyrepository.miami.edu/oa_dissertations/431.

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Advances in recent nanoscience technologies have generated a new compilation of biocompatible, fluorescent nanoparticles derived from semiconductor quantum dots (QDs). QDs are extremely small in size and possess very large surface areas, which gives them unique physical properties and applications distinct from those of bulk systems. When exposed to biological fluid, these QDs may become coated with proteins and other biomolecules given their dynamic nature. These protein-QD systems may affect or enhance the changes in protein structure and stability, leading to the destruction of biological function. It is believed that these QDs can act as nucleation centers and subsequently promote protein fibril formation. Protein fibrillation is closely associated with many fatal human diseases, including neurodegenerative diseases and a variety of systemic amyloidoses. This topic of protein-QD interaction brings about many key issues and concerns, especially with respect to the potential risks to human health and the environment. Herein, the behavioral effects of dihydrolipoic acid (DHLA)-capped CdSe/ZnS (core/shell) QDs in hen egg-white lysozyme (HEWL) and human serum albumin (HSA) protein systems were systematically analyzed. This study gives rise to a better understanding of the potentially useful application of these protein-QD systems in nanobiotechnology and nanomedicine as a bioimaging tool and/or as a reference for controlled biological self-assembly processes.

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Zane, Andrew Paul. "The Synthesis and Behavior of Positive and Negatively Charged Quantum Dots." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1316472706.

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Salverson, Lynsey Alexandra-McLennan. "An Engineering Approach Investigating the Uptake and Phytotoxicity of One Type of Engineered Nanoparticle (CdSe/ZnS Quantum Dots) by Solanum lycopersicum." Digital Commons at Loyola Marymount University and Loyola Law School, 2012. https://digitalcommons.lmu.edu/etd/42.

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The novel and extraordinary physiochemical properties of engineered nanoparticles (ENPs) are certain; however, their unique characteristics raise growing concerns regarding potentially adverse effects on biological and ecological systems. It is becoming increasingly evident that, before the full potential of nanotechnology can be realized, standardized characterization of ENP behavior, fate, and effects on the ecosystem are essential to ensure the safe manufacturing and use of ENP products. Otherwise, the promise of such extraordinary advancements may find itself limited to applications such as electronics and sporting equipment, industries in which ENPs currently reside. The current toxicity profile of engineered nanomaterials is not only preliminary, but highly variable amongst researchers. Consequently, there is great need for the development of a highly organized, efficient, and precise approach to assess the hazardous potential ENPs may pose, while addressing the safety concerns surrounding and limiting nanotechnology. In response to such concerns, the present study took an engineering approach, in an otherwise traditionally viewed discipline, to assess the potential impact of one type of engineered nanoparticle, water-soluble (MUA) CdSe/ZnS- quantum dots (QDs), on tomato (Solanum lycopersicum) seedlings, by implementing a full factorial design of experiment (FDOE), in an effort to identify which factors, and their interactions, have a significant (p ≤ 0.05) effect on root and shoot elongation, and if any observed effects are a result of particle uptake, evaluated via fluorescence microscopy imaging. By implementing factorial experimental design methodologies, not only are we efficiently identifying the factors that affect phytotoxicity, we are providing, for the first time to our knowledge, the first scientific data to report the significant interaction effects between the factors responsible for ENP toxicity. (MUA) CdSe/ZnS quantum dots had a negative influence on root and shoot lengths of tomato seedlings exposed for 3 days, as well as those exposed for 6 days. The observed influence depended on QD concentration and exposure time, as statistical analyses found QD concentration, exposure time, and the concentration-exposure time interaction significantly (p ≤ 0.05) affected root and shoot lengths of tomato seedlings. Additionally, to minimize the observed phytotoxicity effects (i.e., to maximize tomato root lengths), our results suggest that exposure of tomato seeds to low QD concentration levels (125 mg/L) for short periods of time (maximum of 3 days) to yield maximum root lengths of approximately 2.21 cm, that is – minimal phytotoxicity effects.

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Waurisch, Christian. "Thermodynamic and kinetic investigations into the syntheses of CdSe and CdTe nanoparticles." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-91768.

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This thesis addresses the syntheses towards high quality CdSe and CdTe nanoparticles. Therefore, thermodynamic and kinetic aspects of the hot injection method are investigated. By means of the introduction of a thermodynamically less favored nuclei species the nucleation event of CdSe quantum dot synthesis is affected. Utilizing highly reactive tin or lithium silylamides, primarily formed SnSe or Li2Se nuclei undergo a cation exchange to the demanded CdSe particles. The further growth proceeds without the incorporation of the so called quasi-seed species. In this manner, the mechanism of the cation exchange-mediated nucleation is proven and optimized with respect to the required amount of the quasi-seed species. Furthermore, this protocol is applied to up-scaling attempts to reduce the efforts for optimization to a minimum. Following this, a successful laboratory batch up-scaling is achieved by increasing flask size as well as precursor concentrations by factors of 2 and 10, respectively. A further possibility to thermodynamically influence the hot injection synthesis is the activation of the precursor species. By altering the injection pathway, as compared to the standard synthesis, the precursor species are differently coordinated and hence possess different thermodynamic stabilities. Investigations on the system of CdTe quantum dots lead to the result of a cation activation by the use of the thermodynamically less stable carboxylate ligands instead of phosphonates. Additionally, anion activation is suggested due to a kind of aging of the phosphine ligands via their oxidation by phosphonic acids. Furthermore, it is found that the ratio of Cd-to-Te strongly influences the formation of so called magic-sized clusters. Following the results, the smallest detectable species is determined as a cluster species with a size of 1.8 nm. The role of the magic-sized clusters is not fully resolved, but the initial growth is assumed to occur via monomer deposition onto or the fusion of the observed clusters. On the other hand, cluster dissolution is thermodynamically forced by the decreasing monomer concentration and can simply be explained by the process of Ostwald ripening via the creation of a smaller cluster species. Mechanistically this is explained by the formation of configurational deviations from the ideal closed-shell structure. Finally the inorganic coating of the core quantum dots in investigated. Therefore, homoepitaxial coating is employed to overcome the limit in particle size by introducing additional monomer supply. As a result, following the classical crystallization theory, defined injections of precursor material during the diffusion limited growth regime allow a fine tuning of the final particle size. Nevertheless, homoepitaxial coating inevitably leads to photoluminescence quenching, whereas heteroepitaxial growth usually improves the optical quality. By means of a type I structure, CdSe/CdS/ZnS, the successive ion layer adsoption and reaction mechanism is discussed. Furthermore, alloy structures of CdSe/ZnSe with a radially gradated intermediate shell of CdZnSe are achieved by postsynthetic high temperature treatments. This annealing induces internal diffusion processes and allows exactly adjusting the emission wavelength due to defined shrinkage of the initial core size during the alloying process.

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Graham, Amy L. "Characterization of Heterojunctions via X-Ray and UV Photoemission Spectroscopy: Energy Level Implications for Single and Mixed Monolayer SAMs, CdSe Nanoparticle Films, and Organic Semiconductor Depositions." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/195913.

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This work has centered on the interface dipoles arising at heterojunctions between metals, semiconductor nanoparticles, self-assembled monolayers, and organic semiconductor materials. Alkanethiol self-assembled monolayers, CdSe nanocrystals, and the organic semiconductors zinc phthalocyanine (ZnPc) and Buckminster fullerene (C60) were the basis of these investigations. UV photoemission spectroscopy has proven to be an invaluable tool to observe the vacuum level shifts for these analyses while using XPS to corroborate surface structure. With a full evaluation of these surfaces, the shifts in the vacuum level, valence ionizations, and core ionizations, the impact of these interfaces, as well as their influence on the subsequent deposition of organic semiconductor layers is established.Alkanethiols possessing varying dipole moments were examined on gold and silver substrates. The viability of these alkanethiols was demonstrated to predictively adjust the work function of these metals as a function of their intrinsic dipole moments projected to surface normal, and established differences between Ag--S and Au--S bonds. The capability of the SAMs to modify the work function of gold provided an opportunity for mixed monolayers of the alkanethiols to produce a precise range of work functions by minimal adjustments of solution concentration, which were examined with a simple point dipole model.Photoemission spectroscopy offers a thorough analysis of CdSe nanoparticle films. Despite a plethora of research on these nanocrystals, there still is controversy on the magnitude of the shift in the valence band with diameter. In our research we found the majority of the valence band shift could be attributed to the interface dipole, ignored previously. Meanwhile, the valence band tethered films was obscured by the sulfur of the thiol tether.Finally, organic semiconductor layers deposited on SAMs on gold exhibited various interface dipole effects at these heterojunctions. Charge transfer states of ZnPc did not favor energy level alignment on the SAM/Au substrates used; C60 demonstrated vacuum level shifts on C15 and C12ph alkanethiol monolayers consistent with the interface charge transfer (ICT) model. These results provide credibility to models recently demonstrated in the literature for other passivated metal surfaces, and include the viability of SAMs in these discussions.

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Darugar, Qusai A. "Surface effects on the ultrafast electronic relaxation of some semiconductor and metallic nanoparticles." Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-06272006-160645/.

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Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2007.
Zhang, John, Committee Member ; Wang, Zhong, Committee Member ; El-Sayed, Mostafa, Committee Chair ; Orlando, Thomas, Committee Member ; Lyon, Andrew, Committee Member.

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Poppe, Jan. "Spectroelectrochemical Investigations of Semiconductor Nanoparticles." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-162122.

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The ability to tune the electronic band gap of semiconductor nanoparticles or “quantum dots” by controlling their size simply by variation of the synthetic conditions has opened many possibilities for applications across a wide range of fields. Many of these applications, such as solar cells, catalysis, sensing and light emitting diodes involve charge transfer processes between the nanoparticles and an adjacent phase. In order to make that charge transfer as efficient as possible, knowledge pertaining to the absolute energy positions of the electronic levels of such nanoparticulate materials is of primary relevance. The determination of these values and the important parameters that influence them was therefore the central issue of the present work. An electrochemical approach was chosen so that the data obtained could be referred to an absolute energy scale.The ability to tune the electronic band gap of semiconductor nanoparticles or “quantum dots” by controlling their size simply by variation of the synthetic conditions has opened many possibilities for applications across a wide range of fields. Many of these applications, such as solar cells, catalysis, sensing and light emitting diodes involve charge transfer processes between the nanoparticles and an adjacent phase. In order to make that charge transfer as efficient as possible, knowledge pertaining to the absolute energy positions of the electronic levels of such nanoparticulate materials is of primary relevance. The determination of these values and the important parameters that influence them was therefore the central issue of the present work. An electrochemical approach was chosen so that the data obtained could be referred to an absolute energy scale. To achieve reliable measurements a new strategy was developed so that dense and homogeneous monolayers of semiconductor particles could be deposited onto transparent electrodes. The films were obtained by exchanging the original bulky ligand shell of the nanocrystals with a reactive alkoxysilane species and subsequent immersion of the substrate into a solution of the modified nanocrystals. SEM and electrochemical investigations have shown a much higher coverage efficiency in comparison with other methods presently established in the literature, which are based on the approach of prefunctionalizing of the substrates prior to coating. Fractional coverages of 80 % were obtained within 24 h while avoiding the time consuming and complicated step of functionalizing the substrates before deposition. Films of CdSe and CdS nanoparticles deposited on fluorine doped tin oxide (FTO) electrodes were characterized by means of potential modulated absorption spectro-scopy (EMAS). Employing this special spectroelectrochemical technique, bleach signatures in the absorption spectra of the quantum dots induced by electron injection into their respective conduction band states were investigated. The features observed in the spectra and the evaluation of the potential dependence of the signal intensity revealed that only the lowest conduction band state, namely the 1Se state, is populated. The occupancy follows a quasi Fermi-Dirac distribution whose distributional width, in addition to the temperature, also depends on the size distribution of the particle ensemble investigated. On that basis a model was developed to extract the electrochemical potentials of the respective populated lowest conduction band states. For CdSe quantum dots the four energetically lowest excitonic transitions were found to become bleached as the 1Se state is populated, indicating that these transitions promote electrons from different states in the valence band to the same conduction band state. These findings are in excellent agreement with results obtained from ultra fast optical pump probe experiments, which are methods that usually demand much more experimental efforts than the technique presented in these studies. The determination of the potential of the 1Se state versus a known reference potential allows one to map the top valence band states with respect to an absolute energy scale. This provides the opportunity to compare the energy positions obtained for different samples. Determination of the electrochemical band edge potential clearly features a size dependent shift of the conduction band edge and the valence band edge for both CdSe and CdS quantum dots, which is in excellent agreement with the expected behavior due to the quantum confinement effect. Investigations in different electrolytes have shown that the immediate environment has a major impact on the electrochemical potentials of the energy levels of the nanoparticles. This observation is particularly important from a technological point of view, as in many applications the semiconductor material is in direct contact with an electrolyte as for example in quantum dot sensitized solar cells, electrochemical sensors and catalysis. In contrast to other “purely physical” methods such as photoelectron spectroscopy or scanning tunneling spectroscopy, potential-modulated absorption spectroscopy provides the ability to probe the materials under their most likely “working” conditions where such environmental influences can be directly taken into account. Further, it has been shown that potential modulated absorption spectroscopy can be applied to bulk semiconductor electrodes, as long as they are thin enough to allow adequate amounts of light to pass through. The features observed in the EMAS spectra of these samples clearly differ from those obtained for nanoparticle films, as in such materials a continuum of states is progressively filled rather than a single state. Besides band-filling the potential modulation additionally induces changes in the absorption, which can be attributed to the Franz-Keldysh effect resulting from the modulation of the electric field across the space charge layer. The resolution and sensitivity that one can obtain with this comparatively simple and cost-effective setup is quite remarkable. As has been demonstrated it was possible to achieve clearly resolved bleach spectra of submonolayers of quantum dots attached to FTO with optical densities below 0.001. Recently it has been reported that cyclic voltammetry (CV) can be used to study the size dependent positions of the electronic levels of quantum dots. The intention of the last part of this thesis was to reproduce this work for the nanoparticles investigated within this thesis in order to compare the results with those obtained by EMAS. However, the experiments undertaken here reveal that the anodic and cathodic peaks observed in the cyclic voltammograms cannot automatically be assigned to the absolute band edge positions of the particles as the size dependent peak positions and their potential differences do not show any evidence for a correlation with respect to the quantum size effect. Rather the voltammetric responses reflect the solid state electrochemical characteristics of CdSe. Theoretical considerations concerning the response expected in a CV due to band filling of semiconductor nanoparticles confined to an electrode surface revealed that the expected currents are quite similar to that of a pseudo-capacitance. However, pronounced signals are only obtained if appropriate amounts of deposited nanoparticles are present which are electronically addressable without hampering the charge transfer. Hence a clear assignment of the peaks obtained in a cyclic voltammogram to the electronic band edges without employing a complementary technique to confirm ones findings therefore seems to be at best questionable.

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Hao, Junjie. "Revisiter la chiralité induite et la photodéposition d'or sur des semi-conducteurs CdSe/CdS possédant différentes morphologies contrôlées." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0186.

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Des morphologies contrôlées de nanocristaux de semi-conducteurs II – VI traditionnels à base de cadmium (NCs) sont présentées. Différentes morphologies peuvent être obtenues en utilisant le processus d'extraction et de purification à la tri-n-octylphosphine (TOP), tels que les nanodots, les nanofleurs, les têtards, les bâtonnets (dot-in-rods) et les tétrapodes. Les objets appelés CdSe/CdS (DRs) ont été spécifiquement choisis pour la poursuite de l'étude sur la chiralité et la photodéposition en raison de leur chiralité potentielle induite par le ligand et de leurs performances catalytiques. Le mécanisme de transmission chirale induite par un ligand a été étudié par un procédé top-down de gravure de domaine sélectif. Les résultats ont montré que lors de la comparaison des signaux de chiralité d'une nanoparticule individuelle, la couche de coquille avait un impact négatif sur la chiralité du premier pic d'exciton, mais une corrélation positive sur la chiralité d'absorption de la coquille. Nous présentons pour la première fois les signaux de luminescence à polarisation circulaire (CPL) de chiralité induite dans des nanoplaquettes deCdSe / CdS (NPL) synthétisées par une approche en une étape. La chiralité des nanocristaux semi-conducteurs de morphologies différentes induite par le ligand est étudiée plus en détail, et les activités de dichroïsme circulaire (CD) et de CPL observées sont étroitement associées aux caractères géométriques des nanostructures tels que l'épaisseur de la coque et le rapport d'aspect des NR CdSe/CdS . Enfin, le mécanisme de croissance par photodéposition induite par laser de nanocristaux d'or sur des bâtonnets préformés de CdSe/CdS (DRs) est abordé. Les nanoparticules HNPs Au-CdSe/CdS sont obtenues en utilisant une lumière laser bleue. Les effets du capteur de trous pour la synthèse des HNPs à pointe unique sont étudiés en profondeur pour la première fois. De plus, d'autres paramètres sont également étudiés, tels que l'intensité d'irradiation, le temps de dépôt, le rapport Au / DRs, etc. Nos résultats sont en bon accord avec un modèle développé pour la croissance d'un seul nanocristal Au en surface du DR
Controlled morphologies of traditional cadmium-based II–VI semiconductor nanocrystals (NCs) are presented. Different morphologies can be achieved by using the tri-n-octylphosphine (TOP) extraction and purification process, such as nanodots, nanoflowers, tadpoles, dot-in-rods and tetrapods. CdSe/CdS dot-in-rods (DRs) were specifically chosen for the further study on chirality and photodeposition due to its potential ligand-induced chirality and catalytic performances. The mechanism of ligand-induced chiral transmission was studied by the top-down selective domain etching process. The results showed that when comparing the chirality signals of an individual nanoparticle, the shell layer had a negative correlation with the first exciton peak chirality, but positive correlation with the shell absorption chirality. We present the induced chirality circularly polarized luminescence (CPL) signals in CdSe/CdS nanoplates (NPLs) synthesized by a one-pot approach for the first time. The ligand induced chirality of semiconductor nanocrystals with different morphologies are further studied, and the observed circular dichroism (CD) and CPL activities are closely associated to the geometrical characters of the nanostructures such as the shell thickness and the aspect ratio of the CdSe/CdS Tadpoles. Finally, the laser-induced photodeposition growth mechanism of gold nanocrystals onto preformed CdSe@CdS dot-in-rods (DRs) is presented. The hybrid NPs (HNPs) Au-CdSe/CdS are achieved by using a blue-laser light. The effects of the hole scavenger for the synthesis of single-tipped HNPs are studied deeply for the first time. Additionally, other parameters are also studied, such as the irradiation intensity, the deposition time, the Au/DRs ratio and so on. Our results compare quite well with a model developed for the growth of single Au nanocrystal

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16

Castro, Nicolò. "Auto-assemblage de nanoparticules Janus." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS486/document.

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L’expression "Nanoparticules Janus" est utilisée pour se référer aux nanoparticules colloïdales faites de deux moitiés qui présent deux propriétés physiques et/ou chimiques différentes. Au cours des dernières années, plusieurs études théoriques ont été publiées sur les possibilités d’auto-assemblage offertes par ces particules (en particulier par Sciortino, F. et al.), mais peu de travail expérimental a été fait sur ce sujet. Les études théoriques suggèrent que beaucoup de comportements intéressants apparaissent quand la taille des particules s’approche de la portée d’interaction des forces en jeu (des dizaines de nanomètres dans le cas des forces de Van der Waals et des forces hydrophobes). Dans ce manuscrit, nous montrons la formation d’agrégats des hétérodimères de Au–SiO₂ d’une taille inférieure à 100nm. L’auto-assemblage a été déclenché par un échange du ligand hydrophile sur la surface de l’or par un ligand hydrophobe induisant une interaction attractive. L’assemblage a été suivi par spectroscopie d’absorption résolue dans le temps et diffusion des rayons X aux petits angles. Nous avons constaté que les thiols les plus courts ont une période d’induction plus longue et forcent les particules à se rapprocher davantage, comparé à des thiols avec des chaînes plus longues. Nous étudions également un second système : des nanoplaquettes de CdSe. Celles-ci sont des objets quasi-2D en matériau semiconducteur avec des propriétés optiques uniques. Ces propriétés résultant de leur taille réduite dans une dimension. Du fait de leur nouveauté et de leur particularité, leur nucléation et le remarquable mécanisme de croissance de ces particules sont toujours étudiés. Ainsi nous avons suivi leur synthèse par SAXS et WAXS in situ, afin d’obtenir des informations en ce qui concerne ces deux étapes, et notamment d’étudier la déformation de certains de ces systèmes sous forme de feuillets enroulés de CdSe. Les nanoplaquettes de CdSe ont été aussi utilisés pour créer des structures hybrides CdSe–Au. La combinaison de ces deux matériaux a déjà montré des effets uniques, comme une meilleure efficacité catalytique et, combiné avec la dimension réduite et le contrôle des plaquettes, pourrait aboutir à des caractéristiques encore plus intéressantes. Nous proposons une méthode de synthèse qui aboutit à la formation de petites sphères d’or sur les coins des plaquettes. Nous montrons que la taille des sphères dépend de la quantité de précurseur utilisée, et des images de microscopie électronique à haute résolution mettent en évidence la structure cristalline des deux matériaux
"Janus nanoparticles" is the term used to refer to colloidal nanoparticles made of two halves with different physical and chemical properties. Over the last years, several theoretical studies have been published on the self-assembly possibilities offered by these particles (in particular by Sciortino, F. et al.), but little experimental work has been done on them. The theoretical studies suggest that many interesting behaviors appear when the size of the particles approaches the interaction range of the forces at play (tens of nanometers in the case of van der Waals and hydrophobic forces). In this manuscript, we show the formation of clusters of Au–SiO₂ heterodimers with sizes of less than 100nm. The self-assembly was induced by exchanging the hydrophilic ligand on the Au surface with a hydrophobic one, which provided the attractive interaction. The assembly was followed by time-resolved absorption spectroscopy and small-angle X-ray scattering. We found that shorter thiols have a longer induction period, and cause the particles to come closer together, compared to thiols with longer tails. We also study a second system: CdSe nanoplatelets. These are semiconducting quasi-2D structures with unique optical properties. These properties result from their reduced size in one of the dimensions. Because of their novelty and particularity, the nucleation and growth mechanism of these particles is still being studied. We followed the synthesis using in-situ SAXS and WAXS, to obtain information with regards to this mechanism and to study the deformation which occurs in some of these systems which leads to rolled up sheets of CdSe. The CdSe nanoplatelets were also used to create hybrid CdSe–Au structures. The combination of these two materials has already proven to produce unique effects such as enhanced catalysis and, combined with the reduced dimensionality and control of the platelets, could result in even more interesting characteristics. We propose a synthesis method which results in the formation of small gold spheres on the corners of the platelets. We show that the size of the spheres depends on the amount of precursor used, and show high resolution electron microscopy images which highlight the crystalline structure of both materials

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Power, Christian. "Caracterización de nano materiales de CdSe, CdTe y Cd0. 5Mn0. 5Te formados por ciclos de presión." Toulouse 3, 2006. http://www.theses.fr/2006TOU30265.

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La présente étude a pour objet la formation et caractérisation structurale et morphologique de nanoparticules semi-conductrices de CdSe, CdTe y Cd0. 5Mn0. 5Te, à partir de la phase solide monocristalline, par application de cycles de pression, à T=300K, (schéma Top Down). Les pressions maximales appliquées sur les échantillons sont inférieures à 11GPa, elles furent obtenues par l'utilisation d'une cellule de grand volume type Paris-Edimbourg. Les échantillons récupérés furent caractérisés par diffraction de rayons X, microscopie électronique en transmission, diffraction électronique et dispersion Raman et nous avons pu déterminer que nos nano matériaux ainsi formés sont approximativement sphériques de diamètre inférieur à 50nm. Nos mesures magnétiques obtenues par magnétomètre SQUID et sous champ magnétique pulsé montrent qu'à basses températures le comportement de nos nanoparticules de Cd0. 5Mn0. 5Te, est régit par une contribution ferromagnétique des spins de surface, se superposant au comportement spin glass
This research propose the formation and structural and morphologic characterization of nanoparticles semiconductors of CdSe, CdTe and Cd0. 5Mn0. 5Te, from your solid phase mono crystal in bulk, for the cycles of pressure applications to T=300K (way Top Down). The maximum pressures applied are under of 11GPa, using the cell of great volume type Paris-Edinburgh. The sample recovers were characterized using diffraction of X–rays, electronic microscopic of transmission, diffraction electrons and Raman dispersion, and it achieve to determine that they are spherical nanoparticles with average diameter lower 50nm. With the SQUID Magnetometer and magnetization in the High Magnetic Field Pulsed, we determined the behavior of the nanoparticles of Cd0. 5Mn0. 5Te to low temperatures and this is guided by ferromagnetic contribution of the spin of surface, that put on top on behavior of spin glass

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18

Geitner, Nicholas. "A Study of Gold Nanoparticles for Application in Semiconductor CdS Nanosheet Biosensor Devices." Miami University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=miami1311893825.

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Sih, Bryan Christian. "Gold and cadmium selenide (CdSe) nanoparticles capped with oligothiophenes." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/31523.

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The preparation and characterization of hybrid materials composed of oligothiophene-capped Au and CdSe nanoparticles with novel chemical, structural, electronic and optical properties are reported. α-Phosphino-oligothiophenes (12-15 and 23) and thiol-substituted oligothiophenes (26, 29, 32) were prepared by metal-catalyzed coupling reactions and studied using absorption and emission spectroscopy, and cyclic voltammetry. These functionalized oligothiophenes were used to passivate the surface of Au (16-19) and CdSe (CdSe-26, CdSe-29, CdSe-32) nanoparticles. Oligothiophene-capped Au nanoparticles were prepared directly by reducing a Au salt in the presence of the phosphino-oligothiophene. Attachment to the Au nanoparticles has little effect on the electronic structure of the oligothiophene as determined from the absorption spectra. On the other hand, the oligothiophenes appear to affect the electronic structure of the Au nanoparticle, as observed via a red-shift in the surface plasmon absorption. Electrochemical oxidation of the phosphino-terthiophene capped Au nanoparticles lead to crosslinking where the nanoparticles are linked both structurally and electronically by observed increases in conjugation, conductivity and plasmon coupling relative to the unlinked particles. The oligothiophene bridge linking the Au nanoparticles is shown to facilitate plasmon coupling between adjacent nanoparticles. The crosslinked material also demonstrates tunable conductivity where the conductivity in the material can be increased by oxidative doping of the π-conjugated bridge. Oligothiophene-capped CdSe nanoparticles were prepared through an exchange reaction between thiol-substituted oligothiophenes and trioctylphosphine oxide-capped CdSe nanoparticles. Attachment of the oligothiophenes to the CdSe nanoparticle has little effect on the electronic structure of the oligothiophene as determined from the absorption spectra. However, the optical properties are significantly affected where the oligothiophene emission is quenched after attachment to the CdSe surface due to either an energy or electron transfer mechanism. Depending on the number of oligothiophenes attached to the CdSe surface, the optical properties of the CdSe nanoparticles are affected differently. An excess number of thiols act as hole traps leading to quenching of the nanoparticle emission. Attempts to electrochemically crosslink these oligothiophene-capped CdSe nanoparticles were unsuccessful possibly due to the intrinsic resistivity in the particles.[See Thesis for Diagrams]
Science, Faculty of
Chemistry, Department of
Graduate

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20

Waurisch, Christian [Verfasser], Alexander Akademischer Betreuer] Eychmüller, Stephen G. [Akademischer Betreuer] Hickey, and Stefan [Akademischer Betreuer] [Kaskel. "Thermodynamic and kinetic investigations into the syntheses of CdSe and CdTe nanoparticles / Christian Waurisch. Gutachter: Alexander Eychmüller ; Stefan Kaskel. Betreuer: Alexander Eychmüller ; Stephen G. Hickey." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://d-nb.info/1067732454/34.

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21

Landes, Christy. "The dependence of the opto-electronic properties of CdSe nanoparticles on surface properties." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/30657.

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Spittel, Daniel, Jan Poppe, Christian Meerbach, Christoph Ziegler, Stephen G. Hickey, and Alexander Eychmüller. "Absolute Energy Level Positions in CdSe Nanostructures from Potential-Modulated Absorption Spectroscopy (EMAS)." American Chemical Society, 2017. https://tud.qucosa.de/id/qucosa%3A33353.

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Semiconductor nanostructures such as CdSe quantum dots and colloidal nanoplatelets exhibit remarkable optical properties, making them interesting for applications in optoelectronics and photocatalysis. For both areas of application a detailed understanding of the electronic structure is essential to achieve highly efficient devices. The electronic structure can be probed using the fact that optical properties of semiconductor nanoparticles are found to be extremely sensitive to the presence of excess charges that can for instance be generated by means of an electrochemical charge transfer via an electrode. Here we present the use of EMAS as a versatile spectroelectrochemical method to obtain absolute band edge positions of CdSe nanostructures versus a well-defined reference electrode under ambient conditions. In this, the spectral properties of the nanoparticles are monitored with respect to an applied electrochemical potential. We developed a bleaching model that yields the lowest electronic state in the conduction band of the nanostructures. A change in the band edge positions caused by quantum confinement is shown both for CdSe quantum dots and for colloidal nanoplatelets. In the case of CdSe quantum dots these findings are in good agreement with tight binding calculations. The method presented is not limited to CdSe nanostructures but can be used as a universal tool. Hence, this technique allows the determination of absolute band edge positions of a large variety of materials used in various applications

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Zane, Andrew P. "Synthesis of Fluorophore Encapsulated Silica Nanoparticles for the Evaluation of the Biological Fate and Toxicity of Food Relevant Nanoparticles." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1408966327.

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Chen, Xiaobo. "Synthesis and Investigation of Novel Nanomaterials for Improved Photocatalysis." Case Western Reserve University School of Graduate Studies / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=case1117575871.

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Pujalte, Igor. "Étude in vitro de la toxicité de nanoparticules métalliques (TiO2, ZnO, CdS) sur la cible rénale." Thesis, Bordeaux 2, 2011. http://www.theses.fr/2011BOR21849/document.

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De nombreuses incertitudes persistent sur la toxicité potentielle des nanoparticules (NPs) et leur devenir dans l’organisme humain. L’objectif de ce travail est de mieux comprendre les mécanismes cytotoxiques induits par des NPs métalliques sur une cible secondaire, représentée par le rein. En effet, les NPs sont susceptibles de franchir les barrières cellulaires, d’être véhiculées par le sang pour se retrouver filtrées par le rein au niveau des cellules glomérulaires et peut-être, réabsorbées au niveau des cellules tubulaires. Cette étude est réalisée in vitro, avec des NPs métalliques de titane (TiO2 : 12 nm), de zinc (ZnO : 75 nm) et de cadmium (CdS : 8 nm), sur cellules mésangiales (IP15) et cellules épithéliales tubulaires (HK-2). Les résultats démontrent des effets variables selon le type cellulaire étudié, la nature chimique des NPs et leur solubilité. Si les NPs insolubles de TiO2 (CI50>100 µg/cm²) ne sont que très peu toxiques, les NPs de CdS et de ZnO le sont bien plus du fait de leur solubilité (CI50<7 µg/cm²). La libération de cations métalliques Cd2+ et Zn2+ est à l’origine de cette toxicité. La production d’ERO et la perturbation du statut oxydatif cellulaire (GSH/GSSG) sont corrélées aux effets cytotoxiques des NPs de ZnO et CdS. Une approche moléculaire permet d’identifier les voies de signalisation cellulaire intervenant dans la réponse au stress (translocation nucléaire des facteurs de transcription : Nrf2 et NF-κB). L’internalisation et l’accumulation, des NPs de TiO2 et de CdS, sont responsables de l’induction d’un stress oxydant et d’un effet cytotoxique lors d’exposition sur le long terme
Many uncertainties remain about the potential toxic effect of nanoparticles (NPs), and their becoming in human organism. The aim of this study was to understand the cytotoxic mechanisms induced by metallic NPs, on a secondary target organ, the kidney. NPs were able to cross biological barriers, be carried in blood to kidney cells, on glomerular or tubular cells. This study was performed in vitro, with NPs of titanium (TiO2: 12 nm), zinc (ZnO: 75 nm) and cadmium (CdS: 8 nm), on mesangial IP-15 cells and epithelial HK-2 cells. Results showed effects depending on cell type, chemical nature of NPs and their solubility. TiO2 NPs have no cytotoxic effect (IC50>100µg/cm²), probably due to their insolubility. Exposure to CdS and ZnO NPs lead to cell death (IC50< 7 µg/ cm²). Release of metallic cations Cd2+ and Zn2+ are the main causes of toxicity. ROS production and disruption of oxidative cellular balance (GSH/ GSSG) were correlated to the cytotoxic effects of ZnO and CdS NPs. A molecular approach was used to identify signaling pathways involved in oxidative stress response (nuclear translocation of NF-kappaB and Nrf2).Internalization and accumulation of TiO2 and CdS NPs were responsible of oxidative stress induction and cytotoxic effect on long term exposure

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Lama, Bimala. "Synthesis and Characterization of CdS Nanoparticle/Polymer Composites." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1375797236.

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27

Rho, Young Gyu. "Quantum-Confined CdS Nanoparticles on DNA Templates." Thesis, University of North Texas, 1998. https://digital.library.unt.edu/ark:/67531/metadc279352/.

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As electronic devices became smaller, interest in quantum-confined semiconductor nanostructures increased. Self-assembled mesoscale semiconductor structures of II-VI nanocrystals are an especially exciting subject because of their controllable band gap and unique photophysical properties. Several preparative methods to synthesize and control the sizes of the individual nanocrystallites and the electronic and optical properties have been intensively studied. Fabrication of patterned nanostructures composed of quantum-confined nanoparticles is the next step toward practical applications. We have developed an innovative method to fabricate diverse nanostructures which relies on the size and a shape of a chosen deoxyribonucleic acid (DNA) template.

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Hancock, Jared M. "Formation and Analysis of Zinc Oxide Nanoparticles and Zinc Oxide Hexagonal Prisms and Optical Analysis of Cadmium Selenide Nanoparticles." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3867.

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In this dissertation, methods to synthesize ZnO are reported. First, zinc oxide nanoparticles were synthesized with small amounts of transition metal ions to create materials called dilute magnetic semiconductors (DMS). We employed a low temperature sol-gel method that produces ZnO nanoparticles of reproducible size and incorporates cobalt, nickel, and manganese ions into the nanoparticles. Conditions were controlled such that a range of amounts of Co, Ni, and Mn were incorporated. The incorporation was tracked by color changes in the white ZnO powder to blue for Co, green for Ni and yellow for Mn. XRD measurements showed the nanoparticles were on the order of 10 nm in diameter and had a wurtzite structure. Magnetic measurements showed a change from diamagnetic to paramagnetic behavior with increasing concentration of metal dopants. Second, formation of ZnO single crystal hexagonal prisms from a sol-gel method is presented. The method required water, zinc acetate, and ethanolamine to create a gel of zinc hydroxide and zinc hydroxide acetate, which upon heating formed single crystal hexagonal prisms. Characterization of the gel was done by XRD as well as XRD high temperature chamber (HTK) to determine the role of temperature in prism formation. SEM images showed hexagonal prisms were of uniform size (0.5 × 2 µm.) TEM and electron diffraction images showed a change from randomly oriented particles to an ordered single crystal after heating. Water and the acetate salt of zinc proved to be critical to prism formation. Lastly, we report absorption and fluorescence properties of synthesized oligothiophenes and oligothiophene-ruthenium complexes that are bound to CdSe nanoparticles. Their ability to act as sensitizers and charge transfer junctions was tested. It was found that fluorescence of CdSe nanoparticles was quenched when they were bound to the oligothiophenes, and that the fluorescence of the oligothiophenes was also quenched. The fluorescence lifetimes of the quenched species were shortened.

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Alves, João Paulo de Carvalho. "Estudos fotofísicos e fotovoltaicos de sistemas polímero-fulereno e nanopartículas de CdSe." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/248463.

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Orientadores: Ana Flávia Nogueira, Teresa Dib Zambon Atvars
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química
Made available in DSpace on 2018-08-19T07:00:55Z (GMT). No. of bitstreams: 1 Alves_JoaoPaulodeCarvalho_M.pdf: 2190959 bytes, checksum: a321ebe05ad04c15ea1e77782b12c743 (MD5) Previous issue date: 2011
Resumo: Células solares orgânicas apresentam-se como uma alternativa promissora para conversão de energia solar. Muitos desses dispositivos são produzidos pela mistura de um polímero condutor e um derivado fulereno. O polímero condutor atua como absorvedor de luz, doador de elétrons e transportador de buracos, enquanto o fulereno atua como transportador e aceitador de elétrons. Esses dispositivos destacam-se pela possibilidade de deposição em substratos flexíveis, transparência, diversidade em cores e uso de materiais recicláveis, além do baixo custo. No entanto, células solares orgânicas apresentam baixa mobilidade de carga e absorção em pequena faixa espectral da energia solar quando comparadas aos dispositivos fotovoltaicos baseados em semicondutores inorgânicos. A adição de CdSe ao sistema P3HT/PCBM promoveu o decréscimo na eficiência e fotocorrente dos dispositivos. Esses resultados são diferentes dos observados para o sistema PFT/PCBM, previamente reportado. A diferença observada para os dispositivos com os polímeros P3HT e PFT foram associados com as diferentes interações polímero-nanopartícula, como evidenciado pelas medidas de absorção e emissão e pelos espectros de RMN. A elevada concentração de tiofeno no P3HT pode contribuir fortemente na formação de um complexo entre polímero e CdSe e na desativação do processo de transferência de elétrons entre polímero e PCBM. Para investigar um possível efeito de morfologia pela introdução de CdSe ao sistema P3HT/PCBM, foram obtidas imagens de microscopia de força atômica e microscopia óptica. Há um aumento da rugosidade e tamanho de grãos do sistema com o acréscimo de nanopartículas de CdSe, que pode inibir o processo de separação de cargas e de formação de redes de percolação
Abstract: Organic solar cells are presented as a promising alternative for solar energy conversion. Many of these devices are produced by mixing a conductive polymer and a fullerene derivative. The conducting polymer acts as a light absorber, electron donor and hole transporter, while the fullerene acts as acceptor and electron shuttle. These devices call attention due to the possibility to produce flexible solar cells with high transparency and different colors, allied to the use of recyclable materials and low cost. However, organic solar cells have lower charge mobility and narrower spectral range absorption of solar energy compared to inorganic-based photovoltaic devices. The addition of CdSe to the P3HT/PCBM system promoted the decrease in efficiency and photocurrent of the devices. These results are different from those observed for the PFT/PCBM system, previously reported. The difference observed for the devices with P3HT and PFT was associated with different polymer-nanoparticle interactions, as evidenced by absorption and emission measurements. The high concentration of thiophene in P3HT contributes in the formation of a complex between polymer-CdSe and the deactivation of the electron transfer process between the polymer and PCBM. To investigate the possible contribution of a morphological effect induced by CdSe in P3HT/PCBM system, Atomic Force Microscopy (AFM) images were obtained. There is an increase of roughness and grain size of the system with the addition of CdSe nanoparticles, which can inhibit the charge separation process and formation of percolation networks
Mestrado
Quimica Inorganica
Mestre em Química

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Yang, Zhiqiang. "Preparation of palladium, palladium sulfide, cadmium selenide nanoparticles and magnesium oxychloride, magnesium hydroxide nanorods." Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/891.

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Chauviré, Timothée. "Développement de systèmes photochimiques à base de Quantum Dots hydrosolubles de type coeur CdSe et coeur-coquille CdSe/ZnS." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENV039/document.

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L'utilisation de nanoparticules semi-conductrices colloïdales, appelées quantum dots, est nouvelle pour des applications en photocatalyse redox. Ces nano-objets possèdent une forte absorption dans le visible modulable avec leur taille. De plus, la présence d'une couche de ligands peut rendre ces nanostructures éco-compatibles. Dans ce manuscrit de thèse, une étude de la photocatalyse redox avec des nanoparticules cœur CdSe et cœur-coquille CdSe/ZnS a été réalisée dans le visible en solvant aqueux. Les quantum-dots hydrosolubles sont tout d'abord fonctionnalisés par des ligands de type acide aminé. Trois systèmes photochimiques ont ensuite été testés avec les substrats suivants : dérivés d'acides aminés, vanilline et 8oxodG. L'activité photochimique des nanoparticules semi-conductrices a pu être démontrée et évaluée par la détection de produits de réaction. Le mécanisme de transfert de charge photoinduit a par ailleurs été élucidé par des techniques spectroscopiques durant l'irradiation
The use of colloidal semiconductor nanoparticles, called quantum dots, is recent in redox photocatalysis. Those nanostructures exhibit strong and size depending visible absorption properties. The ligand shell on the nanoparticle surface can be furthermore managed to realize green applications. Thus the study of redox photocatalysis with core CdSe nanoparticles and core-shell CdSe/ZnS was carried out with visible light in aqueous solvent. Firstly, we synthetized hydrophilic quantum-dots stabilized by amino acids ligands. Secondly, we perform three different studies of photocatalytic systems with the following substrates : modified amino acids, vanillin and 8oxodG. The nanoparticle's photochemical activity was first demonstrated and evaluated by the detection of photochemical products. The photoinduced charge transfer mechanism was elucidated during irradiation by spectroscopic techniques

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Dagtepe, Pinar. "Quantized growth of semiconductor nanoparticles, investigation of aggregation dynamics and the growth kinetics." Diss., Kansas State University, 2010. http://hdl.handle.net/2097/4321.

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Doctor of Philosophy
Department of Chemistry
Viktor Chikan
Colloidal semiconductor nanoparticles will be important and practical next generation materials that can be cheaply manufactured. The objective of this project is to gain more inside into chemistry is used to control the formation and assembly of semiconductor nanoparticles (NPs). As a model system CdSe and CdTe nanoparticles are used in this work. The growth kinetics, aggregation dynamics, and heterogeneous growth of NPs by using novel tools such as; in-situ monitored fluorescence and absorption techniques, time-resolved and static fluorescence spectroscopy, TEM (transmission electron microscopy), and numerical simulations are studied. This study can be divided into the following four parts. The first part presents experimental observation of the quantized growth of CdTe quantum dots (QD). The high-temperature absorption spectra indicate the evolution of multiple peaks corresponding to various sizes of QDs. The observed aggregation is driven by dipole-dipole interaction of NPs. The second part is an investigation of the aggregation dynamics of magic-sized CdTe quantum dots and how this process can be controlled. It is shown that the growth kinetics of the QDs is very sensitive to the Cd/Te ratio. Cd-rich conditions form very different aggregation pattern due to the lack of formation of magic-sized nanoparticles. Simulations also suggest that the formation mechanism is mainly coalescence of the particles rather than the ‘neck formation’ within the CdTe aggregates. The next part investigates the growth of NPs in the presence of two distinctly sized NPs in the bimodal growth regime via numerical simulations. The bimodal distribution (or quantized Ostwald ripening) technique is found to be a slower process than the repeated injection technique to focus the size distribution of NPs. Slower growth will reduce inhomogeneity in a scaled-up production of NPs. The last part focuses on the effect of addition of doping on vii heterogeneous growth and the growth kinetics. The low temperature synthesis lacks the heterogeneous growth regime. However, as the temperature is increased to 120 0C, two different sizes emerge. Addition of In dopants seems to accelerate the growth kinetics and the magic sized NPs in the solution possess a negative anisotropy that is most likely due to supperlatice formation of magic-sized NPs.

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Hendel, Thomas. "Synthese und Charakterisierung von Halbleiter- und Metall-Nanopartikeln und deren Selbstassemblierung in 3-dimensionale Netzwerkstrukturen." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17571.

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Aus CdTe- und Edelmetallnanopartikeln werden 3-dimensionale Netzwerkstrukturen aufgebaut, welche durch einen überkritischen Trocknungsprozess zu hochporösen, weitverzweigten Halbleiter-Metall-Nanokompositen, sogenannten Aerogelen, umgewandelt werden. Zunächst werden Thiol-stabilisierte CdTe- und Edelmetallnanopartikel im wässrigen Milieu hergestellt und deren Morphologie und optischen Eigenschaften umfangreich mittels UV-Vis-Spektroskopie, Fluoreszenzspektroskopie und -lebensdauermessung, ICP-OES, TEM, STEM-EDX und AFM charakterisiert. Als Metallkomponente kamen Gold-, Palladium- sowie bimetallisch gemischte Gold-Palladium-Nanopartikel zum Einsatz. Die Gelierung der Nanopartikellösungen erfolgt durch Vermischen der Kolloide und anschließender kontrollierter Destabilisierung mithilfe einer Xe-Dampflampe oder der Zugabe von Wasserstoffperoxid. Neben einer mechanistischen Beschreibung der Gelbildungsmethoden wurden die resultierenden Hydrogele und die aus der überkritischen Trocknung erhaltenen Aerogele bezüglich Zusammensetzung, Morphologie und optischen Eigenschaften mithilfe von TEM und REM jeweils gekoppelt mit EDX-Analyse, Stickstoff-Porosimetrie, diffuser Reflexionsspektroskopie, Fluoreszenzspektroskopie und Fluoreszenzlebensdauermessungen untersucht. Weiterhin wird die UV-Vis-Spektroskopie als Methode zur Konzentrationsbestimmung von Gold in Lösungen kolloidaler Gold-Nanopartikel validiert. Dabei wird die Absorption der Kolloide bei einer Wellenlänge von 400 nm als Maß verwendet. Die NP-Lösungen werden anhand der Parameter Partikelgröße, Oberflächenfunktionalität und der Oxidationsstufe des enthaltenen Goldes variiert.
3-dimensional network structures are formed combining CdTe and noble metal nanoparticles. A supercritical drying process allows production of highly porous and widely branched semiconductor-metal nanohybrids, so-called aerogels. Primarily, thiol-capped CdTe and noble metal nanoparticles are synthesized in aqueous media and their morphology and optical properties are studied extensively using UV-Vis and fluorescence spectroscopy, time-resolved fluorescence spectroscopy, ICP-OES, TEM, STEM-EDX and AFM. The metal entity involves gold and palladium nanoparticles as well as bimetallic mixed Au/Pd nanoparticles. After mixing of the different colloids gelation is induced by a controlled destabilization process using a Xenon lamp irradiation or the addition of hydrogen peroxide. Gelation techniques are described mechanistically. Resulting hydrogels and aerogels which are obtained by supercritical drying approach are characterized concerning composition, morphology and optical properties using TEM and SEM each coupled with EDX, nitrogen porosimetry, diffuse reflection spectroscopy, fluorescence spectroscopy and time-resolved fluorescence spectroscopy. Moreover, the UV-Vis spectroscopy is validated as a method to determine the gold concentration in gold nanoparticle solutions using the colloids absorbance at 400 nm as a measure. Gold nanoparticle solutions are varied concerning the parameters particle size, surface functionality and oxidation state of contained gold.

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Dimitriev, O., V. Petrenko, Yu Slominski, and I. Mazarchyk. "Formation of J-aggregates of Thiamonomethincyanine Dyes in the Presence of CdTe Nanoparticles." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35442.

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The conditions of formation of J-aggregates for three types of thiamonomethincyanine dyes, whose structure is differed by end groups, are studied depending on their concentration and type of interaction with CdTe nanoparticles with size of about 3 nm in aqueous dispersions. The influence of dye structure on the efficiency of formation of J-aggregates in solutions and in films was found. It was found that quantum dots (QDs) of CdTe stabilized by thioglycolic acid can adsorb J-aggregates of the dye molecules on their surface. It was shown for the first time that the hybrid structure of dye-CdTe can be formed through the interaction of negatively charged dye molecules and negatively charged surface of the QDs through the formation of neutral aggregates. It was not found any processes of energy transfer from dye to the particles of CdTe neither for the dimer - CdTe system nor for the J-aggregates – CdTe system. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35442

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Suryajaya. "Study of electrostatically self-assembled thin films of CdS and ZnS nanoparticle semiconductors." Thesis, Sheffield Hallam University, 2007. http://shura.shu.ac.uk/20410/.

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In this work, CdS and ZnS semiconducting colloid nanoparticles coated with organic shell, containing either SO[3-] or NH[2+] groups, were deposited as thin films using the technique of electrostatic self-assembly. The films produced were characterized with UV-vis spectroscopy and spectroscopic ellipsometry - for optical properties; atomic force microscopy (AFM) - for morphology study; mercury probe - for electrical characterisation; and photon counter - for electroluminescence study. UV-vis spectra show a substantial blue shift of the main absorption band of both CdS and ZnS, either in the form of solutions or films, with respect to the bulk materials. The calculation of nanoparticles' radii yields the value of about 1.8 nm for both CdS and ZnS.The fitting of standard ellipsometry data gave the thicknesses (d) of nanoparticle layers of around 5 nm for both CdS and ZnS which corresponds well to the size of particles evaluated from UV-vis spectral data if an additional thickness of the organic shell is taken into account. The values of refractive index (n) and extinction coefficient (k) obtained were about 2.28 and 0.7 at 633 nm wavelength, for both CdS and ZnS.Using total internal reflection (TIRE), the process of alternative deposition of poly-allylamine hydrochloride (PAH) and CdS (or ZnS) layers could be monitored in-situ. The dynamic scan shows that the adsorption kinetic of the first layer of PAH or nanoparticles was slower than that of the next layer. The fitting of TIRE spectra gavethicknesses of about 7 nm and 12 nm for CdS and ZnS, respectively. It supports the suggestion of the formation of three-dimensional aggregates of semiconductor nanoparticles intercalated with polyelectrolyte. AFM images show the formation of large aggregates of nanoparticles, about 40-50 nm, for the films deposited from original colloid solutions, while smaller aggregates, about 12-20 nm, were obtained if the colloid solutions were diluted. Current-voltage (I-V) and capacitance-frequency (C-f) measurements of polyelectrolyte/nanoparticles (CdS or ZnS) films suggest the tunnelling behaviour in the films while capacitance- voltage (C-V) and conductance-voltage (G-V) measurements suggest that these nanoparticles are conductive. The electroluminescence was detected in sandwich structures of (PAH/CdS/PAH)[N] using a photon counting detector, but not in the case of ZnS films.

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Mohamad, Syed Abdul Malik Syed. "Electrical studies on hybrid MIS structures incorporating CdS nanoparticles in organic films." Thesis, Sheffield Hallam University, 2005. http://shura.shu.ac.uk/20004/.

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This project involves the investigation of a.c. and d.c. electrical characterisations and low-frequency noise properties of Langmuir-Blodgett (LB) films in metal-insulator-semiconductor (MIS) structure. Two types of insulating films based on hybrid organic-inorganic materials sandwiched between metal and semiconductor were fabricated. The original insulating films (untreated) were 40 layers Y-type LB films of Cd-salt stearic acid (CdSt[2]). The second type of insulating films were formed after the treatment of CdSt[2] films with H[2]S gas over a period of 12 hours at room temperature to grow CdS nanoparticles within the stearic acid matrix (treated). The capacitance-voltage (C-V) measurement of CdSt[2] LB films exhibit significant dependence on the measurement frequency in the accumulation region due to high d.c. leakage currents. By embedding CdS nanoparticles into the stearic acid matrix, less frequency dependent C-V curves were obtained. The problem in determining the true insulator capacitance due to frequency dispersion was overcome by using the Yang's model. The corresponding dielectric constant of LB films of CdSt[2] was found to be 2.3 and increased to 5.1 when embedded with CdS nanoparticles. The results from the dielectric loss measurement show that both devices agree well with Goswami and Goswami model. By incorporating CdS nanoparticles in the stearic acid matrix, the dielectric loss was found to increase which could be due to electrons being trapped by the CdS nanoparticles. A large current density was observed in the untreated devices at room temperature giving evidence of a leaky dielectric. The analysis of the temperature dependent I-V characteristics shown that current is independent of temperature, similar to the results published by several researchers which explained the current conduction mechanism in term of electron hopping and tunnelling through each bilayer of the LB films. In contrast, by embedding the CdS nanoparticles in the stearic acid matrix the currents have reduced by one-order of magnitude. The temperature dependence of the I-V characteristics showed the dependence of current on the device temperature at low electric field densities whilst less temperature dependence was observed at higher electric field density. Further investigation into the carrier transport mechanism, has found that the Poole-Frenkel effect was the dominant mechanism in the treated devices. A low frequency noise measurement setup has been designed and validated. The results of low-frequency noise measurement reported here are new. 1 / f noise was the only low-frequency noise observed in treated and untreated devices for frequencies up to 1kHz. The current noise spectral density S[I](f), was found to fit well with themodified Hooge's empirical model; [mathematical formula] where C, /, and f are noisemagnitude, current and frequency respectively. The exponential values of gamma and beta were found to lie within the acceptable ranges of 0.7 < gamma < 1.4 and 1 < beta < 3 respectively. The current noise power spectral density (PSD) at several fixed bias current was found to be dependent on the bias current with the PSDs for treated devices found to be approximately two-orders of magnitude higher. These results show that low-frequency noise measurement can be used to probe into the microstructure of the electron devices. It is believed that by embedding the CdS nanoparticles into the stearic acid matrix, electron trapping centres have been created which result in different current conduction behaviour from the untreated LB films of cadmium stearate.

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Mousavi, R. A., A. A. Sepahy, and M. R. Fazeli. "Biosynthesis, Purification and Characterization of Cadmium Sulfide Nanoparticles Using Enterobacteriaceae and their Application." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/34903.

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The area of nanotechnology encompasses the synthesis of nanoscale materials, the understanding and the utilization of their physicochemical and optoelectronic properties, and the organization of nanoscale structures into predefined superstructures. The development of biologically inspired experimental processes for the synthesis of nanoparticles is evolving into an important branch of nanotechnology. Nanotechnology has recently emerged as an elementary division of science and technology that investigates and regulates the interaction at cell level between synthetic and biological materials with the help of nanoparticles. A wide range clean, nontoxic and eco-friendly synthesis of nanoparticles is an important aspect of current nanotechnology. Microbial synthesis of nanoparticles is a Green chemistry approach that interconnects nanotechnology and microbial biotechnology. Microorganisms play an important role in the eco-friendly synthesis of metal nanoparticles. This study illustrates the synthesis of CdS nanoparticles using the bactetia of Enterobacteriaceae ( Escherichia coli PTCC 1533 and Klebsiella pneumonia PTCC 1053) after 96 h of incubation at room temperature (30ºc) and pH 9. The morphology of the samples was analyzed using Scanning electron microscopy(SEM). The size of CdS nanoparticles in aqueous solution has been calculated using UV–Vis spectroscopy, XRD, FTIR, EDS and SEM measurements. The nanoparticles are found to be polydisperse in the size range 5–200 nm. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/34903

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38

Saviot, Lucien. "Etude par diffusion Raman du confinement des vibrations optiques et acoustiques dans des nanoparticules de CdSe et de silicium poreux." Lyon 1, 1995. http://www.theses.fr/1995LYO10134.

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L'interpretation des spectres d'absorption de particules de semi-conducteur de quelques dizaines de nanometres de rayon par le confinement quantique des electrons est aujourd'hui bien etablie. L'objet de cette these est de caracteriser la nature des vibrations acoustiques et optiques qui existent dans de telles structures. L'investigation de ces vibrations a ete realisee par spectroscopie raman resonante qui permet entre autre la determination des energies de vibration. Les limites d'une approche quantitative de ces structures consistant a prendre en compte la taille finie uniquement par l'intermediaire de la rupture de la conservation de l'impulsion au cours du processus raman ont ete etablies. La partie theorique consiste donc en la recherche des modes propres de vibration acoustiques et optiques en fonction de la taille des particules. Les resultats dans les cas ou les atomes a la surface des particules sont libres de tout mouvement ou fixes ont ete developpes ce qui permet de faire jouer un role a la nature de l'interface particule matrice dans l'interpretation des spectres experimentaux. La partie experimentale s'articule essentiellement autour de l'analyse des spectres raman obtenus pour des nanoparticules de cdse. Pour reproduire les spectres de diffusion, un modele d'elargissement des raies a ete propose. Il prend en compte un elargissement homogene dependant de la taille et un elargissement inhomogene du a la contribution au spectre raman des differentes tailles contenues dans l'echantillon etudie. Ce modele a permis de reproduire quantitativement les spectres des modes acoustiques pour cdse. Dans le cas du silicium poreux et pour les modes optiques de cds et cdse, le modele est qualitativement en accord. L'evolution des spectres avec la temperature ainsi que les effets de resonance dans cdse et cds sont egalement abordes. Malgre le fait que cds et cdse soit des materiaux tres semblables, leur spectre raman resonant different sensiblement. En particulier, une excitation selective de taille a ete observee a temperature ambiante pour cds et pas pour cdse

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Junior, João Batista Souza. "Síntese de nanoestruturas core/shell de Co/Au magnetoplasmônica e pontos quânticos de CdSe/ZnS." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/75/75134/tde-28072017-170738/.

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Nanomateriais apresentam propriedades ajustáveis pelo seu tamanho e forma, como o fenômeno de superparamagnetismo em nanopartículas magnéticas ou o confinamento quântico dos portadores de carga em pontos quânticos (quantum dots). Assim, a síntese de nanopartículas esféricas monodispersas torna-se um fator extremamente importante, haja visto que tais propriedades podem ser ajustáveis para diferentes aplicações na área de tecnologia e biomedicina. Nanopartículas magnéticas e quantum dots podem ser apontados como promissores materiais para diagnóstico e terapia de neoplasias (câncer), e o desenvolvimento desses sistemas busca, atualmente, intensificar a magnetização e a eficiência de emissão, respectivamente, relativo às propriedades magnéticas e ópticas, além de outros requisitos. Neste trabalho, nanopartículas esféricas de cobalto metálico foram sintetizadas com diâmetro médio de 5,3 nm e desvio padrão de 0,4 nm, distribuição de tamanhos lognormal. A equação de Langevin modificada pelo modelo de partículas interagentes foi utilizada no ajuste da curva de magnetização M(H) para obtenção do diâmetro magnético médio e desvio padrão, 4,7 nm e 1,0 nm, respectivamente. Comparando os dois diâmetros, encontra-se uma camada morta de magnetização de aproximadamente 3,0 Å a qual, praticamente, não contribui para a magnetização da amostra, sendo a magnetização de saturação de 125 emu g-1. Nanoestruturas core/shell de Co/Au apresentaram a propriedade de ressonância plamon de superfície, uma propriedade adicional também desejada para aplicações biomédicas, sendo este sistema denominado magnetoplasmônico. Quantum dots de CdSe foram sintetizados como elevado controle de tamanho e forma. Utilizando rotas de síntese diferentes dos clássicos procedimentos denominados TOP-TOPO, e dióxido de selênio como precursor, estudos mostraram que na presença de um agente redutor no meio de reação e do solvente 1-octadeceno, as amostras apresentaram melhores propriedades óticas. A estrutura cristalina das amostras de CdSe corresponde à formação da fase blenda de zinco, diferentemente das sínteses TOP-TOPO que levam à formação da fase hexagonal wurtzita. A cinética de crescimento dos quantum dots de CdSe também foram avaliadas através de alíquotas retiras com o tempo de reação mostrando um crescimento exponencial do diâmetro das partículas, como previsto pelas teorias de nucleação e crescimento. Estudos por microscopia de fluorescência mostraram que os quantum dots apresentaram o comportamento de intermitência de fluorescência relatado na literatura como um dos fatores que levam a uma diminuição do rendimento quântico de fluorescência. Nanoestruturas core/shell de CdSe/ZnS foram obtidas com elevado controle da espessura da camada de recobrimento e a intensificação das propriedades de fotoluminescência foram mostradas. Os objetivos do trabalho foram alcançados com sucesso, onde foi possível observar a estabilização e a intensificação da magnetização da fase de cobalto metálico, pouco relatado na literatura. Ainda, foi possível conferir maior estabilidade química, versatilidade de funcionalização da superfície e uma segunda propriedade de ressonância plasmônica com o recobrimento com ouro, sem grande prejuízo da propriedade magnética. Em relação aos sistemas ópticos, os semicondutores de CdSe foram obtidos por nova rota de síntese com expressivo controle de tamanho e forma, recobertos com ZnS intensificando as propriedades ópticas do sistema.
Nanomaterials properties are size- and shape-controlled, such as the superparamagnetism phenomenon of magnetic nanoparticles or the quantum confinement of charge carriers of quantum dots. Therefore, synthesis of monodisperse spherical nanoparticles became extremely important over the past few deacades, since nanoparticles can be used for plenty of applications in technology and biomedicine. Magnetic nanoparticles and quantum dots are promising materials for diagnosis and therapy of cancer. Spherical nanoparticles of metallic cobalt were synthesized with mean diameter of 5,3 nm and standard deviation of 0,4 nm, lognormal distribution. A modified Langevin equation using the interacting superparamagnetic model was used to fit magnetization curves obtaining the mean magnetic diameter and standard deviation, 4,7 nm and 1,0 nm, respectively. The difference between these two diameters was assigned to the magnetic dead layer (∼3.0 Å), which does not contribute to the sample magnetization, being the saturation magnetization of cobalt nanoparticles around 125 emu g-1. Co/Au core/shell nanostructures were synthesized and the surface plasmon ressonance property was observed, an additional property also desired for biomedical applications, being the Co/Au core/shell system called magnetoplasmonic. CdSe quantum dots were synthesized with high size- and shape-controlled. Using different synthetic routes from the classic TOP-TOPO synthesis, and selenium dioxide as a precursor, the results show that and reducing agent is necessary and 1-octadecene solvent leads to better optical properties. CdSe samples showed a zinc blend (cubic phase) crystal structure, different from TOP-TOPO syntheses that leads to wurtzite structure (hexagonal phase). The growth kinetics of CdSe particles were also evaluated through aliquots from reaction showing exponential growth of particles diameter, as predicted on the theory of nucleation and growth. Fluorescence microscopy studies showed that quantum dots exhibited fluorescence intermittence behavior already reported in the literature as one fo the reasons for the quantum yield decrease. CdSe/ZnS core/shell nanostructures were obtained with high control of the coating layer thickness and the increase of the photoluminescence properties were shown.

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Olubummo, Adekunle A. [Verfasser], Wolfgang H. [Akademischer Betreuer] Binder, and Robson F. [Akademischer Betreuer] Storey. "Controlling the location of polymer functionalized (CdSe) nanoparticles in mixed lipid-polymer membranes / Adekunle A. Olubummo. Betreuer: Wolfgang H. Binder ; Robson F. Storey." Halle, Saale : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2014. http://d-nb.info/1054328625/34.

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Omar, Zaahira. "The safety and toxicity of MPA-CdTe quantum dots in legume plants." University of the Western Cape, 2017. http://hdl.handle.net/11394/6259.

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Magister Scientiae - MSc (Biotechnology)
The expansion of nanotechnology, resulting in multitudes of consumer and industrial products, causes concern amongst the scientific community regarding the risks associated with the release of nanomaterials into the environment and its subsequent effects on plants. Therefore, the focus of this study was aimed at investigating the effects of MPA-capped CdTe and carbon QDs on legumes plants namely P. vulgaris and G. max. Fluorescent imaging revealed that QDs were translocated from the roots to the aerial parts of the plant and accumulated in the edible parts of P. vulgaris. Subsequent physiological and biochemical tests revealed that both QD types induced oxidative stress as biological markers for stress including lipid peroxidation and cell death were elevated. In addition, carbon QDs displayed lower toxicity in comparison to MPA-CdTe QDs, but still possessed the ability to induce oxidative stress in plant cells. However, the effects were more pronounced in G. max in comparison to P. vulgaris; and more so with MPA-CdTe QDs than carbon QDs. Furthermore, MPA-CdTe and carbon QDs altered the concentrations and translocation of essential macro and microelements that are required for plant growth and development. This may have detrimental effects on crop productivity and yield, with negative implications on food quality and food security.
2021-08-31

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Garcia, Saida Y. "A Characterization of CdS/Polymer Interactions by Solid State Nuclear Magnetic Resonance." University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1240277763.

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Alterary, Seham. "Synthèse, caractérisation et fonctionnalisation de CdS et de suspensions magnétiques collïdales en vue d'application biomolécules." Paris 7, 2008. http://www.theses.fr/2008PA077230.

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Lors de cette thèse, deux axes ont été développés. La première partie du manuscrit a été consacrée au développement de nanocristaux pour des applications biologiques, Dans un premier temps, nous avons réussi la synthèse de nanoparticules de CdS_fonctionnalisées par des oligothiophènes carboxylates. Ces ligands carboxyliques forment une couche compacte autour des nanocristaux ce qui permet leur dispersion dans l'eau. Ces nano-structures fonctionnalisées ont été caractérisées par différentes techniques. La taille des particules peut être contrôlée entre 2 et 4 nm. La fonctionnalisation par la biotine a été réalisée grâce un ester activé, le N-hydroxysuccinimide. Des essais de détection de l’ayidine ont démontré la capacité de ces particules à détecter une substance biologique. La deuxième partie du manuscrit est focalisée sur le développement de nouvelles structures nanométrique core-shell. Dans cette partie nous avons mis au point une méthode de synthèse sol-gel pour l'encapsulation homogène des nanoparticules magnétiques d'une couche de silice dont l'épaisseur est contrôlable. Les nanoparticules cœur magnétique et écorce silice sont ensuite caractérisées par différentes méthodes physico-chimiques. Nous avons réussi à démontrer, clairement la possibilité d'élaborer des nanoparticules structurées présentant un cœur magnétique et une écorce de silice
Semiconductor quantum dots (QDs) are a new generation of inorganic probes with advantageous properties over traditional organic probes for biological applications. A major hurdle in the use of QDs for biology is the inability of the hydrophobically synthesized QDs to interface with aqueous environments. In the first part of this dissertation we describe the synthesis of water-soluble CdS QDs end-capped with N-hydroxysuccinimide ester groups, with narrow size distribution. These CdS QDs are synthesized in polyol medium using terthiophene dicarboxylic acid as a stabilizer. The structure of the hybrid product was investigated by TEM, XRD, optical and FTIR spectroscopy. The modifîed nanoparticles consist of a few tens of oligothiophène units attached to the CdS core. The free carboxylic end groups were transformed into 7V-hydroxysuccinimidyl ester and were further cross-linked with biotin and avidin. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy results indicate successful modification of CdS QD surfaces. The second part, describes the synthesis and the characterization of hybrid magnetic core-shell structures. The Stöber method bas been adopted to prepare hybrid core-shell particles by coating the surfaces of monodisperse magnetic emulsion with uniform silica shells. The Stöber method has been adopted to prepare hybrid core-shell particles by coating the surfaces of monodisperse magnetic emulsion with uniform silica shells. The coated particles have been characterized by electron microscopy (TEM), XPS spectroscopy and IR and showing a core shell structure with a uniform layer of silica

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Hroch, Daniel. "Vertikálně uspořádaná pole CdS nanotyčinek pro aplikace v solárních článcích." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-254222.

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This thesis describes the deposition of nanoparticles into nanoporous alumina templates. Nanoparticles of cadmium sulphide were chosen thanks to wide band gap of 2,45 eV. CdS is desired semiconductor promising better efficiency when comes to solar radiation conversion to useful energy. Theoretical part consists of explanation of photovoltaic principles, band-gap theory of materials, currently available technologies to manufacture solar cells and their efficiencies. Next part introduces the approaches of manufacturing nanoporous templates from aluminium (Anodized Aluminium Oxide, AAO) in details together with options to deposit cadmium sulphide into these structures. There is also brief description of deposition based on vacuum filtration. Experiments were made in Laboratory of Microsensors and Nanotechnologies at Faculty of Electrical Engineering and Communication in Brno University of. The experimental chapter describes manufacturing process of AAO and deposition via vacuum filtration. Samples were evaluated by Scanning Electron Microscopy.

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Krasselt, Cornelius, Jörg Schuster, and Borczyskowski Christian von. "Photoinduced hole trapping in single semiconductor quantum dots at specific sites at silicon oxide interfaces." Universitätsbibliothek Chemnitz, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-122745.

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Blinking dynamics of CdSe/ZnS semiconductor quantum dots (QD) are characterized by (truncated) power law distributions exhibiting a wide dynamic range in probability densities and time scales both for off- and on-times. QDs were immobilized on silicon oxide surfaces with varying grades of hydroxylation and silanol group densities, respectively. While the off-time distributions remain unaffected by changing the surface properties of the silicon oxide, a deviation from the power law dependence is observed in the case of on-times. This deviation can be described by a superimposed single exponential function and depends critically on the local silanol group density. Furthermore, QDs in close proximity to silanol groups exhibit both high average photoluminescence intensities and large on-time fractions. The effect is attributed to an interaction between the QDs and the silanol groups which creates new or deepens already existing hole trap states within the ZnS shell. This interpretation is consistent with the trapping model introduced by Verberk et al. (R. Verberk, A. M. van Oijen and M. Orrit, Phys. Rev. B, 2002, 66, 233202).

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Das, Prajna Paramita. "Enhancement of photoactivity by synthesizing nanotube-nanoparticle composites of TIO₂ and CdS for generation of hydrogen via splitting of water." abstract and full text PDF (UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1460754.

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Maxwell, Deborah Bolin. "Iron Molybdenum Cofactor: Catalyst in Dihydrogen Production and NifEN's Role in the FeMo-co Biosynthetic Pathway." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5432.

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Humankind's tremendous industrial and technological progress over the last two centuries has been driven by the natural abundance and availability of fossil fuels. As those reserves deplete, the prudent course of action would be to develop other readily available fuel sources. Some research efforts using biomolecules involve the hydrogenases and nitrogenases with the goal of evolving dihydrogen. At the nitrogenase active site, the iron-molybdenum cofactor (FeMo-co) catalyzes the reduction of dinitrogen and protons to form ammonia and dihydrogen. Toward the goal of producing dihydrogen passively as an alternative fuel, a novel advanced material has been developed. CdSe nanoparticles complexed with FeMo-co, in both aqueous and organic solvent systems showed complex formation. When the system was interrogated by EPR spectroscopy, evidence of electron transfer was observed. The CdSe-MSA?NafY?FeMo-co system when illuminated with visible light evolved dihydrogen consistently in four different experimental sets under the same reaction conditions. NifEN protein plays an important role in the biosynthesis of FeMo-co in addition to the involvement of NifU, NifS, NifB, NifX, NifH and NafY. After NifB synthesizes a FeMo-co precursor, 6-Fe NifB-co, NifEN further incorporates additional Fe, S, Mo, and (R)-homocitrate to complete the synthesis of FeMo-co. Molybdenum is provided to NifEN as its oxoanion, Mo(VI)O42-; however, in FeMo-co molybdenum is in the oxidation state of Mo(IV). EPR spectroscopic investigation of NifEN turnover samples showed a signal at g = 2.00 that was dependent on molybdate concentration. Power and temperature profiles gave evidence that the g = 2.00 EPR signal was distinct from the Fe-S clusters in NifEN. The species observed at g = 2.00 was assigned to the reduction of Mo(VI) to Mo(V). How to utilize the effectiveness of FeMo-co and complex it to photoactive materials for the purpose of evolving dihyrogen upon illumination, thus providing a sustainable alternative energy source is one subject of this dissertation. A related subject is to gain an understanding of the biosynthetic pathway of FeMo-co by investigation of NifEN turnover experiments. This understanding should contribute towards the development of improved catalysts for meeting future energy demands.
Ph.D.
Doctorate
Chemistry
Sciences
Chemistry

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Paudel, Nava R. "Nanoparticle-aided Radiation Therapy: Micro-dosimetry and Evaluation of the Mediators Producing Biological Damage." University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1403142628.

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van, Embden Joel Leonard. "Synthesis and optical properties of CdSe core and core/shell nanocrystals." 2008. http://repository.unimelb.edu.au/10187/3225.

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The synthesis of nanocrystals is unique compared to the formation of larger micron-sizesspecies as the final crystal sizes are not much larger than the primary nuclei. As a consequencethe final outcome of a nanocrystal synthesis i.e mean crystal size, concentrationand standard deviation is almost solely determined by the end of the nucleation phase. Directingthe growth of crystals beginning from aggregates of only tens of atoms into maturemonodisperse nanocrystals requires that the governing kinetics are strictly controlled at everymoment of the reaction. To effect this task various different ligands need to be employed,each performing a particular function during both nucleation and growth. (For complete abstract open document)

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(7373747), Muchuan Hua. "Optical refrigeration on CdSe/CdS quantum dots." Thesis, 2019.

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Implementation of optical refrigeration (OR) in quantum dot (QD) materials was achieved for the first time. An OR experiment was designed and carried out in our lab and a maximum temperature drop around 0.68 K was observed in the zinc-blende crystalline CdSe/CdS (core/shell structure) QD samples under laser excitation. The cooling effect was achieved by utilizing the energy up-conversion photoluminescence (PL) of CdSe/CdS QDs with sub-band excitation. While the cooling efficiency of the system was estimated and optimized by a semi-empirical model built during this research.

This work has proved the capability of QD materials to be used as a cooling substance for OR, which significantly expanded the possible candidates for OR. The technique could have many applications, such as harvesting cooling effect from sun light with the help of metamaterials, which can produce quasi-monochromatic light. It may also be used to cool QD in optical traps, which leading may help to develop new ultra-sensitive sensors and application for quantum information science.

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Dissertations / Theses on the topic 'CdSe nanoparticle'

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