Journal articles: 'Ultraviolet spectra, Photons, X-ray diffraction'

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Fu, Chang Feng, Lian Fu Han, Chao Liu, and Xi Ming Chen. "Structural and Optical Properties of Zn_1-XCr_XO Thin Films Deposited by Magnetron Sputtering." Materials Science Forum 687 (June 2011): 750–55. http://dx.doi.org/10.4028/www.scientific.net/msf.687.750.

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In this study, Zn1-xCrxO thin films were successfully fabricated on glass substrates by magnetron sputtering technique. The relationship between Cr doping concentration and the structural and optical characteristics of the produced samples was investigated by X-ray diffraction (XRD), optical transmittance and photoluminescence(PL). EDS results demonstrate that Cr ions are substitutionally incorporated into ZnO. XRD analysis reveals that all the prepared films with a preferential c-axis orientation exhibit the wurtzite structure of ZnO. The spectrometer transmittance data indicates that the band gap energies of the Zn1-xCrxO films are calculated by a linear fitting method. The band gap is found to be large with the increasing dopant concentration. The PL spectra suggest that all the samples have an ultraviolet emission peak centered at 370 nm. With the improved Cr-doped concentration, the peaks of ultraviolet emission have a blue shift to the region of higher photon energy, which is coincident with those values calculated by the linear fitting from the transmittance data. It is also found that the intensity of ultraviolet emission has been remarkably improved when Cr content is approximately 2.0at.%, but it is decreased when doping concentration of Cr is excessively high.

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Bulus, I., J. K. Sheyin, E. Yayock, and A. S. Dalhatu. "Nd3+ CONCENTRATION DEPENDENT OPTICAL FEATURES OF GADOLINIUM BOROPHOSPHO-TELLURITE GLASSES." Open Journal of Physical Science (ISSN: 2734-2123) 1, no. 1 (March 10, 2020): 1–10. http://dx.doi.org/10.52417/ojps.v1i1.84.

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Improving the optical response of glass host with two or more strong network formers via suitable controlled of rare earth ions is the key issue in the fabrication of optical based glass for solid state lasers and light emitting devices. Hence, we report the Nd3+ concentration dependent on optical parameters such as absorption edge, optical band gap (direct and indirect) and Urbach’s energy of gadolinium borophospho-tellurite glasses with chemical composition of 10Gd2O + 30B2O3 + 20P2O5 + (40-)TeO2 + Nd2O3 (where 0.0 ≤ x ≤ 1.0 mol%). The glass samples were synthesized by convectional melt quenching method and characterized through X-Ray Diffraction (XRD) and Ultraviolet Visible Near-Infrared (UV-Vis-NIR) measurements. The amorphous nature of these glasses was confirmed by X-Ray diffraction pattern while the UV-Vis-NIR spectra revealed six absorption peaks corresponding to the transition from ground level 4I9/2 to the various excited state of Nd3+ ions. It was found that the investigated range of Nd3+ doping concentrations has a great influence on aforementioned parameters. The excellent optical features established in the present glass host suggest their potentiality for solid-state lasers and other photonic applications. Bulus, I. | Department of Physics, School of Sciences, Kaduna State College of Education Gidan waya, Kafanchan, Nigeria

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Talib, A., M. K. Ahmad, N. Ahmad, N. Nafarizal, F. Mohamad, C. F. Soon, A. B. Suriani, M. H.Mamat, K. Murakami, and M. Shimomura. "Optimum Reduced Graphene Oxide (rGO) Volume for Hydrothermal Synthesis of Titanium Dioxide (TiO2) Nanostructure Direct Growth on Fluorine-Doped Tin Oxide (FTO)/rGO Substrate." Journal of Computational and Theoretical Nanoscience 17, no. 2 (February 1, 2020): 886–92. http://dx.doi.org/10.1166/jctn.2020.8736.

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Titanium dioxide or titania shows a great interest in solar cell application due to its morphology and crystalline structure. Moreover, it is an affordable compound that could make solar cells more cost economical than traditional silicon solar cells. In this study, the influence of rutile Titanium Dioxide (TiO2) deposit on reduced Graphene Oxide (rGO) as photoanode through one-step hydrothermal technique is demonstrated to synthesis rutile TiO2 nanorods (NRs) and nanoflowers (NFs) morphology in nanoscale dimension with different rGO volume for Dye-sensitized solar cells (DSSCs) application. The successful synthesis of TiO2 on FTO/rGO was confirmed using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX) spectroscopy, ultraviolet-visible (UV-Vis) spectrophotometry and incident photon-to-current conversion efficiency (IPCE) spectra. The performance of dye-sensitized solar cells as outcome of rGO contents in solar cell was also examined. The optimal performance result in contrast with liquid electrolyte based solar cell has been approved over photovoltaic performance study in terms characteristics of open circuit voltage (Voc), short circuit current (Jsc) and solar conversion efficiency.

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Faznny, M. F., Mohamed Kamari Halimah, Amirah Abdul Latif, Farah Diana Muhammad, and Laoding Hasnimulyati. "Optical Properties of La³⁺NPs/Ag⁺ Co-Doped Zinc Borotellurite Glass." Solid State Phenomena 290 (April 2019): 3–8. http://dx.doi.org/10.4028/www.scientific.net/ssp.290.3.

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Lanthanum and silver co-doped zinc borotellurite glasses having chemical composition of [{[(TeO2)0.7(B2O3)0.3]0.7(ZnO)0.3}0.96 (La NPs)0.04]1-x(Ag2O)x with 0.02 ≤ x ≤ 0.10 molar fraction were fabricated via melt-quenching technique. X-ray diffraction (XRD) analysis confirmed the amorphous nature of the samples through the presence of broad hump instead of sharp peaks. Optical properties of the samples were determined through ultraviolet-visible spectroscopy (UV-Vis) in the range of 220 to 800 nm. Fundamental absorption edge observed in the optical absorption spectra shifts to longer wavelength as the concentration of silver in the glass system increases. Decreasing trend for indirect energy band gap and increasing trend of Urbach energy values with the increment of Ag content suggest the contribution of Ag to the formation of nonbridging oxygen. Enhanced optical properties of the prepared glass hints the possible application of the glass material as optical fiber in photonic field.

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Ghoshal, Sib Krishna, Nurul Syuhada Mohamad Zake, Ramli Arifin, Md Rahim Sahar, Md Supar Rohani, and Khaidzir Hamzah. "Optical Properties of Oxy-Chloride Tellurite Glass: Role of Samarium Ions." Advanced Materials Research 1107 (June 2015): 437–42. http://dx.doi.org/10.4028/www.scientific.net/amr.1107.437.

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. Achieving tunable optical properties of inorganic glasses via optimized doping of rare earth ions is ever-demanding in photonics. Control and inhibition of luminescence quenching, nonradiative decay and multi-phonon relaxation responsible of reduction of optical performance remains challenging. Doping/co-doping of different rare earth ions, variation of modifiers and embedding metallic nanoparticles (NPs) are thought as alternative routes to enhance optical response are still underway. We examine the influence of samarium ion concentrations on the optical properties of oxy-chlorite tellurite glasses of the form (70-x)TeO2-15MgO-5Li2O-10LiCl-xSm2O3 with 0.0 x 2.5 mol% prepared using melt-quenching method. The structural and optical characterizations are performed via X-ray diffraction (XRD), Ultraviolet-Visible (UV-Vis) absorption and photoluminescence (PL) spectroscopy. The glass density increased from 4.509 - 4.770 with the increase of Sm2O3 contents from 0.0 2.5 mol %. The XRD spectra confirm the amorphous nature of the glass. The absorption spectra exhibit nine prominent peaks corresponding to the transitions from the ground to excited states and the PL spectra reveal four peaks. The optical energy band gap for direct and indirect transitions are increased and Urbach energy decreased from 3.448 - 3.497, 3.165 - 3.232 and 0.217 - 0.175, respectively with the increase of Sm3+ ion concentrations. Furthermore, the significant enhancement in UV-Vis and PL response display the strong influence of samarium ion on optical and structural properties. The mechanism responsible for enhanced optical properties are analyzed and discussed. The results suggest that our careful experimental studies may contribute towards the development of tellurite glass based solid state lasers.

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Salayová, Aneta, Zdenka Bedlovičová, Nina Daneu, Matej Baláž, Zdenka Lukáčová Bujňáková, Ľudmila Balážová, and Ľudmila Tkáčiková. "Green Synthesis of Silver Nanoparticles with Antibacterial Activity Using Various Medicinal Plant Extracts: Morphology and Antibacterial Efficacy." Nanomaterials 11, no. 4 (April 14, 2021): 1005. http://dx.doi.org/10.3390/nano11041005.

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A green synthetic route for the production of silver nanoparticles (AgNPs) using five different aqueous plant extracts, namely, Berberis vulgaris, Brassica nigra, Capsella bursa-pastoris, Lavandula angustifolia and Origanum vulgare, was investigated in this study. The present work demonstrates the influence of plant extract composition (antioxidant and total phenolic content) on the size and morphology of the produced AgNPs. The biosynthetic procedure was rapid and simple and was easily monitored via colour changes and ultraviolet and visible (UV-Vis) spectroscopy. Subsequently, measurement of zeta potential (ZP), photon cross-correlation spectroscopy (PCCS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) analysis were employed to characterise the as-synthesised nanoparticles. The XRD investigation confirmed the presence of Ag0 in the nanoparticles, and interactions between the bioactive compounds of the plants and the produced AgNPs were evident in the FTIR spectra. TEM indicated that the nanoparticles exhibited a bimodal size distribution, with the smaller particles being spherical and the larger having a truncated octahedron shape. In addition, the antimicrobial activity of the AgNPs was tested against five bacterial strains. All synthesised nanoparticles exhibited enhanced antimicrobial activity at a precursor concentration of 5 mM compared to the control substance, gentamicin sulphate, with the best results observed for AgNPs prepared with B. nigra and L. angustifolia extracts.

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KANOUNI, F., S. AMARA, A. ASSALI, F. ARAB, and Q. ZOU. "TiO2/ZnO PHOTONIC CRYSTAL PREPARED BY SPRAY PYROLYSIS METHOD: APPLICATION TO MULTICHANNEL FILTER." Surface Review and Letters 27, no. 07 (November 29, 2019): 1950181. http://dx.doi.org/10.1142/s0218625x19501816.

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Single-layer titanium dioxide (TiO2, ZnO, double-layer TiO2/ZnO and multilayer TiO2/ZnO/TiO2/ZnO were grown on ordinary glass substrate by ultrasonic spray deposition at 300∘C. Titanium chloride, zinc acetate and deionized water were employed as precursors. The ultraviolet–visible spectrometer spectra show that the quality of optical transmittance in visible wavelength range decreases as the number of bilayers increases. The crystalline phase of the thin films was identified through X-ray diffraction method with diffraction patterns scan used at 2[Formula: see text] from 10∘ to 90∘. From the DRX results, it is found that the crystallinity is enhanced when the number of TiO2/ZnO layers increased. From the 2D/3D atomic force microscopy (AFM) analysis, it is found that the surface of the films was covered by triangle-like particles. However, bilayer and multilayer TiO2/ZnO thin films show smooth and compacted surface roughnesses compared to single-layer TiO2 and ZnO, respectively. In addition to this experimental work, a multichannel filter based on TiO2/ZnO subphotonic crystals is suggested. The transmission properties of this filter have been investigated by means of the transfer-matrix method (TMM). The idea is to import a wedge of air with an apex angle as the defect layer to disturb the original periodicity of the oxide photonic crystal and generate some new kind of multichannel filtering properties.

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Hussein, Ahang M., Elham M. A. Dannoun, Shujahadeen B. Aziz, Mohamad A. Brza, Rebar T. Abdulwahid, Sarkawt A. Hussen, Sarkawt Rostam, Dalia M. T. Mustafa, and Dana S. Muhammad. "Steps Toward the Band Gap Identification in Polystyrene Based Solid Polymer Nanocomposites Integrated with Tin Titanate Nanoparticles." Polymers 12, no. 10 (October 10, 2020): 2320. http://dx.doi.org/10.3390/polym12102320.

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In the current study, the film fabrication of polystyrene (PS) based polymer nanocomposites (NCs) with tuned refractive index and absorption edge was carried out using the solution cast method. X-ray diffraction (XRD) and ultraviolet-visible (UV-Vis) light characterization techniques were performed. The structural and optical properties of the prepared films were specified. The hump of PS decreased significantly when SnTiO3 nanoparticles (NPs) were introduced. Sharp and high intense peaks of SnTiO3 NPs at a high filler ratio were observed. The crystalline size was determined for SnTiO3 NPs from the sharp crystalline peaks using Debye-Scherrer’s equation and was found to be 25.179 nm, which is close enough to that described by the supplier. Several optical parameters, such as absorption coefficient (α), refractive index (n), and optical dielectric properties, were investigated. The absorption spectra were tuned with increasing SnTiO3NPs. Upon the addition of the NPs to the PS host polymer, the absorption edge undergoes shifting to lesser photon energy sides. The optical dielectric constant (ε′) was correlated to the refractive index. The study of the optical band gap was conducted in detail using both Tauc’s model and the optical dielectric loss (ε″) parameter. The results showed that the ε″ parameter is noteworthy to be measured in the optical band gap study of materials.

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Jark, Werner. "A high-efficiency and high-spectral-resolution EUV/soft X-ray monochromator based on off-plane diffraction." Journal of Synchrotron Radiation 27, no. 1 (January 1, 2020): 25–30. http://dx.doi.org/10.1107/s1600577519014462.

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The most efficient diffraction at a periodic grating structure is expected to take place when the incident radiation can be considered to have been specularly reflected off the inclined part of grooves that are positioned parallel to the trajectory of the incident beam. Very encouraging results for this configuration, in which the diffraction takes place off-plane, have been reported recently for a grating to be used in a spectrometer for space science investigations. This grating provided high efficiency for a relatively large groove density and a large blaze angle. High efficiency was observed even in higher diffraction orders up to the fourth order. Here the performance parameters, especially for the combination of diffraction efficiency and achievable spectral resolution, will be discussed for a grating used in a grazing-incidence plane-grating monochromator for monochromatization of synchrotron radiation in the extreme ultraviolet (EUV) and soft X-ray range with photon energies between 30 eV and 2000 eV. It is found that the instrument can provide competitive spectral resolution in comparison with the use of in-plane diffraction. In the case of comparable spectral resolution, the off-plane diffraction is found to provide superior efficiency.

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Jark, Werner. "On the advantages of operation in second-order diffraction of blazed gratings in soft X-ray monochromators." Journal of Synchrotron Radiation 26, no. 5 (August 23, 2019): 1587–91. http://dx.doi.org/10.1107/s1600577519009421.

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The fact that a diffraction grating can provide twofold-smaller bandwidth when operated in second-order diffraction is long known and applied routinely in the laboratory for spectroscopy in the visible and ultraviolet spectral range. A similar routine operation in monochromators for the soft X-ray range is not reported yet. This study will thus address the feasibility of efficient diffraction of soft X-rays in the second order at reflection gratings when operated at grazing angles of incidence. The related systematic study could make profitable use of a recently introduced simple analytical equation for the prediction of the diffraction efficiency of blazed gratings with an ideal sawtooth profile. The predictions are then verified by use of rigorous calculations. The principle finding is that, by operation of gratings with lower groove densities, and thus with higher efficiencies, in higher order diffraction, one can extend the tuning in existing instruments with mechanical/optical limitations to larger photon energies. The performance in terms of transmission and spectral resolving power can be very similar to the performance of a grating with a larger groove density, which would otherwise have to be used for accessing the same energy range. This would allow operation of a single highly efficient grating over a larger photon energy interval at a modern synchrotron radiation source, e.g. from 0.3 to 2.2 keV. Without any requirement for a sophisticated grating exchange scheme, a related instrument promises to be sufficiently stable for the needs imposed by the improvements in source point stability at diffraction-limited storage rings.

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Jark, Werner. "On obtaining high spectral resolution in extreme ultraviolet/soft X-ray monochromators operating off-plane diffraction in a divergent incident beam." Journal of Synchrotron Radiation 27, no. 6 (October 14, 2020): 1499–509. http://dx.doi.org/10.1107/s1600577520011194.

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When the trajectory of an incident beam is oriented parallel to the grooves of a periodic grating structure the radiation beam is diffracted off-plane orthogonal to the plane of incidence. The diffraction efficiency in this condition is very high and in a grating with a sawtooth profile it can approach the reflection coefficient for a simple mirror, when the diffraction order of interest follows the direction for specular reflection at the flat part of the steps. When this concept is used in a plane grating in a monochromator for synchrotron radiation sources, the incident beam is almost always collimated in order to minimize any deterioration of the beam properties due to aberrations, which will be introduced in the diffraction process when an uncollimated beam is used. These aberrations are very severe when the groove density is constant. It will be shown that the effect of these aberrations can be corrected after the diffraction by the use of astigmatic focusing. The latter can be provided by a crossed mirror pair with different focal lengths in the corresponding orthogonal directions. Then a monochromator based on this concept can provide source size limited spectral resolution in an uncollimated incident beam. This is identical to the spectral resolution that can be provided by the same grating when operated at the same position in a collimated incident beam. The source size limited spectral resolution in this case corresponds to a high spectral resolving power of better than ΔE/E = 10 000 for photon energies around 300 eV in the soft X-ray range.

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Bartnik, Andrzej, Wojciech Skrzeczanowski, Henryk Fiedorowicz, Przemysław Wachulak, Tomasz Fok, Łukasz Węgrzyński, and Roman Jarocki. "Photoionized plasmas induced in molecular gases by extreme ultraviolet and X-ray pulses." EPJ Web of Conferences 167 (2018): 03003. http://dx.doi.org/10.1051/epjconf/201816703003.

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In this work a laser-produced plasma (LPP) source was used to create low temperature plasmas. An extreme ultraviolet and soft X-ray (EUV/SXR) radiation pulse was used for ionization of molecular gases, injected into a vacuum chamber synchronously with the EUV/SXR pulse. Energies of photons exceeding 100 eV were sufficient for dissociative ionization, ionization of atoms or even ions. The resulting photoelectrons had also enough energy for further ionizations or excitations. Time resolved UV/VIS spectra, corresponding to single charged ions, molecules and molecular ions, were recorded. For spectral lines, corresponding to radiative transitions in F II and S II ions, electron temperature was calculated based on a Boltzmann plot method. Numerical simulations of the molecular spectra were fitted to the experimental spectra allowing for determination of vibrational and rotational temperatures.

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Cash, Webster. "High Resolution X-ray Spectroscopy: Is It Interesting? Is It Possible?" Highlights of Astronomy 13 (2005): 790–92. http://dx.doi.org/10.1017/s1539299600017135.

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AbstractThe diffraction grating spectra from Chandra and XMM-Newton have given the astronomical community a huge step forward in x-ray spectroscopy of celestial sources. They have proven the scientific richness of the field. But the spectra have resolution of only 300 to 1000 – low by the standards of the visible and the ultraviolet. We discuss some of the exciting new science that can be addressed if spectral resolution of up to 10,000 (or more) can be achieved in the x-ray. We then show how practical, high efficiency, high resolution x-ray spectrographs can be built for high throughput missions like Constellation-X and XEUS.

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Yuh, Jih-Young, Shan-Wei Lin, Liang-Jen Huang, Hok-Sum Fung, Long-Life Lee, Yu-Joung Chen, Chiu-Ping Cheng, Yi-Ying Chin, and Hong-Ji Lin. "Upgrade of beamline BL08B at Taiwan Light Source from a photon-BPM to a double-grating SGM beamline." Journal of Synchrotron Radiation 22, no. 5 (August 8, 2015): 1312–18. http://dx.doi.org/10.1107/s1600577515014009.

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During the last 20 years, beamline BL08B has been upgraded step by step from a photon beam-position monitor (BPM) to a testing beamline and a single-grating beamline that enables experiments to record X-ray photo-emission spectra (XPS) and X-ray absorption spectra (XAS) for research in solar physics, organic semiconductor materials and spinel oxides, with soft X-ray photon energies in the range 300–1000 eV. Demands for photon energy to extend to the extreme ultraviolet region for applications in nano-fabrication and topological thin films are increasing. The basic spherical-grating monochromator beamline was again upgraded by adding a second grating that delivers photons of energy from 80 to 420 eV. Four end-stations were designed for experiments with XPS, XAS, interstellar photoprocess systems (IPS) and extreme-ultraviolet lithography (EUVL) in the scheduled beam time. The data from these experiments show a large count rate in core levels probed and excellent statistics on background normalization in theL-edge adsorption spectrum.

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Adnan, J., M. Arfan, T. Shahid, MZ Khan, R. Masab, AH Ramish, S. Ahtasham, et al. "Synthesis of cadmium hydroxide nanostructure via composite-hydroxide-mediated approach." Nanomaterials and Nanotechnology 9 (January 1, 2019): 184798041985255. http://dx.doi.org/10.1177/1847980419852551.

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Polycrystalline cadmium hydroxide nanomaterials have successfully been synthesized by composite-hydroxide-mediated approach with growth time variation. The influence of growth time on structural, morphological, elemental, and optical properties was explored using X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, and ultraviolet–visible spectroscopy. X-ray diffraction results revealed the hexagonal and monoclinic phases of cadmium hydroxide along with rhombohedral impurity phase of cadmium carbonate. Fourier transform infrared spectroscopy further endorsed the X-ray diffraction results and confirmed the Cd–O bonding vibrations. Time-dependent uniform distribution of spherical morphology was observed in the scanning electron micrographs of the product. The presence of cadmium and oxygen in the energy dispersive X-ray spectroscopy results fingerprinted the purity and formation of the desired nanomaterials. Crystallite size was decreased with the increase of growth time as estimated by the Debye–Scherrer method. Furthermore, the optical bandgap was measured by Tauc’s relation using ultraviolet–visible absorption spectra and found to be in the range of 3.2–3.5 eV.

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Alkhtaby, Lila A. "Structural and Optical Properties of Ti_1-xFe_x O₂ Nanoparticles." Applied Mechanics and Materials 432 (September 2013): 16–19. http://dx.doi.org/10.4028/www.scientific.net/amm.432.16.

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We have synthesized the Ti1-x Fex O2 (x=0.01, 0.02, 0.03 and 0.05) nanoparticles by the sol gel method to enhance the photocatalyic property of TiO2 .These samples are characterized using x-ray diffraction (XRD), Raman spectroscopy, Ultraviolet /Visible (UV/V) spectroscopy and fluorescence spectroscopy (PL). The x-ray diffraction patterns show that all the sample are formed in single phase with a complete solubility of Fe ions in the TiO2 matrix. TiO2 nanoparticles are tetragonal with anatase structure belong to the space group D41h 9 (141 ) /amd Raman active modes appear at 150, 196, 396, 483, 516 and 637cm-1. UV/V spectra show a decrease in the band gap with the increase in Fe concentration from 3.26 eV (1% Fe concentration) to3.11 eV (5% Fe concentration).

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Jia, Ying, Xing Yun Wang, Tian Tian Liu, and Guo Gen Xu. "Preparation of Nanometer ZnO Compound Particles and Ultraviolet Absorption Properties." Advanced Materials Research 571 (September 2012): 43–47. http://dx.doi.org/10.4028/www.scientific.net/amr.571.43.

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ZnO/TiO2 and ZnO/SnO2 composite nanoparticles were prepared by hydrothermal combined-assisted ethanol method , The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer (EDS), and the uv-vis absorption performance of which was also characterized by uv-vis diffuse reflective spectrum (UV-vis). The results of the research showed that, in ultraviolet-visible absorption spectra diffuse, the maximum absorption peaks of ZnO/TiO2 and ZnO/SnO2 nanocomposite particles were blue-shift comparing to the pure nanometer ZnO, and there were also weak absorption in the visible region.

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Yu, Hongquan, Ye Qi, Yanbo Wu, Jinsu Zhang, and Baojiu Chen. "Preparation and Optical Properties of Y2O3:Tb3+ Nanoballs." Journal of Nanoscience and Nanotechnology 16, no. 4 (April 1, 2016): 3886–89. http://dx.doi.org/10.1166/jnn.2016.11829.

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Y2O3:Tb3+ nanoballs were synthesized via the urea homogeneous precipitation method (UPM). The resulting Y2O3:Tb3+ phosphors were characterized by X-ray diffraction (XRD), scanning electron microscopy, ultraviolet-visible (UV-vis) absorption spectra, and general photoluminescence spectra. The particle sizes estimated using X-ray diffractometry and scanning electron microcopy were about 50–200 nm. The emission intensity of the Y2O3:Tb3+ was low when the doping concentrations of Tb3+ were higher. The optimum concentration of Tb3+ for synthesis of Y2O3:Tb3+ nanocrystals is 1%.

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Zhou, Zhi Wei, Ling Fang Qiu, Xiao Bin Qiu, and Shu Wang Duo. "The Synthesis, Characterization and Visible-Light Photodegradation Performance of Graphitic Carbon Nitride Coupling with CoAPO-5." Solid State Phenomena 281 (August 2018): 878–84. http://dx.doi.org/10.4028/www.scientific.net/ssp.281.878.

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In order to enhance hole/electron separation and charge transfer in photocatalysts, the heterostructured g-C3N4/CoAPO-5 hybrids materials were synthesized via a simple grinding method and were investigated using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The optical properties of g-C3N4/CoAPO-5 hybrids materials were measured by ultraviolet-visible diffuse-reflectance spectroscopy (DRS), photoluminescence (PL) spectra and ultraviolet-visible absorption (UV-Vis) spectra. Under visible-light illumination, this work shows the heterogeneous g-C3N4/CoAPO-5 hybrids present a superior photocatalytic activity.

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Li, Mao Hua, Xiao Fei Li, Wen Sheng Ran, and Bo Yang. "The Optical Properties of β-Cyclodextrin-Assisted Synthesize Worm-Like Ag₂S by One Step Hydrothermal Method." Journal of Nano Research 53 (June 2018): 7–12. http://dx.doi.org/10.4028/www.scientific.net/jnanor.53.7.

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The worm-like morphology of silver sulfide (Ag2S) was successfully prepared via hydrothermal reaction at 150°C by using silver nitrate (AgNO3) and thioacetamide(CH3CSNH2) as both the sliver sources and sulfur sources, β-cyclodextrin as the template agent, and water as the solvent. The worm-like of Ag2S are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), x-ray photoelectronspectroscopy (XPS), energy dispersivex-ray (EDX), high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SEAD). Ultraviolet-visible spectra (UV-vis) and photoluminescencespectroscopy (PL) were used in an optical study of the products. The results showed that the existence of β-cyclodextrin is crucial to the formation of worm-like Ag2S, and the optoelectronics test results showed that the sample have a broad absorption in ultraviolet and visible light region.

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Yue, Li Qing, Fu Jun Zhang, Jin Zhao Huang, and Li Wei Wang. "Synthesis and Characterization of ZnS:Mn2+ Nano-Particles for White-Light Emitting." Journal of Nanoscience and Nanotechnology 8, no. 3 (March 1, 2008): 1199–202. http://dx.doi.org/10.1166/jnn.2008.18171.

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The sol–gel method was used to obtain a kind of white-light emitting ZnS:Mn2+ nanoparticles capped by methacrylic acid with an average particle size of ∼7nm. The photoluminescence spectra, X-ray diffraction spectra, Fourier transform infrared reflection spectra and ultraviolet absorption spectra were used to measure their optical properties and crystal structures. The ZnS:Mn2+ nanoparticles with 0.58 wt% Mn2+ concentration emitted white light when excited by 380 nm. The PL spectrum exhibits two emission peaks under irradiation: one at 480 nm generated from the ZnS matrix, and one at 590 nm emitted by the doped Mn2+ ions. The nanoparticles will only emit white light with the optimum Mn2+ concentration (0.58 wt%). X-ray diffraction demonstrates the synthesized ZnS:Mn2+ nanoparticles have zinc blend crystal structure, and the infrared patterns of the capped ZnS:Mn2+ nanoparticles and methacrylic acid are comparable, indicating that the methacrylic polymer has capped or modified ZnS:Mn2+ nanoparticles.

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Liang, Hui, Guang Xian Zhang, Feng Xiu Zhang, Hui Zheng, Ming Lu, and Da Yang Wu. "Super Wettable Poly(Ethylene Terephthalate)(PET) Fabric Modified by UV/Nano-TiO₂/H₂O₂." Applied Mechanics and Materials 184-185 (June 2012): 1272–75. http://dx.doi.org/10.4028/www.scientific.net/amm.184-185.1272.

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The poly(ethylene terephthalate)(PET) fabric was modified by ultraviolet radiation, nano TiO2 and H2O 2 . The results showed that PET fabric could be modified to super wettable fabric, the contact angle of PET fabric irradiated by ultraviolet radiation for 50 min could decrease to 0o in 3.29 second. The Scanning electrical micrograph(SEM) showed there were lots of oxidized products on the surface of modified PET fibers. FT-IR spectra showed modified PET fiber had –COOH, and probably had –NO2. The X-ray diffraction showed the crystallinity increased greatly, and had two new diffraction peaks.

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Wang, Zhijian, Haiming Zhang, Zhijun Wang, Ligong Zhang, Jinshan Yuan, Shenggang Yan, and Chunyan Wang. "Structure and strong ultraviolet emission characteristics of amorphous ZnO films grown by electrophoretic deposition." Journal of Materials Research 18, no. 1 (January 2003): 151–55. http://dx.doi.org/10.1557/jmr.2003.0021.

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Structure and ultraviolet emission characteristics of amorphous ZnO films grown on indium tin oxide coated glass substrates by electrophoretic deposition were investigated using Raman spectra and photoluminescence. The Raman spectrum shows a unique resonant multiphonon process within amorphous ZnO films. The photoluminescence spectrum of amorphous ZnO films shows a strong ultraviolet emission while the visible emission is nearly fully quenched. The transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectrum, and infrared spectrum are used to detect the structure of amorphous ZnO powder. The complex water plays an important role in the photoluminescence intensity emission.

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Григорьев, Л. В., Я. Б. Егорова, Н. А. Быков, А. А. Семенов, and А. А. Никитин. "Оптические и фотолюминесцентные свойства тонкопленочной структуры ZnO-ЦТСЛ в ультрафиолетовом и видимом диапазонах спектра." Журнал технической физики 127, no. 12 (2019): 986. http://dx.doi.org/10.21883/os.2019.12.48697.226-19.

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The results of a study of the structural, optical, and photoluminescent properties of the thin-film structure ZnO/ferroelectric ceramics PLZT are presented. The results of X-ray diffraction analysis of a zinc oxide film synthesized on a PLZT substrate and on a quartz substrate are presented. The transmission spectra, reflection spectra, absorption spectra, and spectral dependence of the photoluminescence of the thin-film structure of ZnO- PLZT and the structure of ZnO-SiO2 in the ultraviolet and visible spectral ranges are presented.

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Li, Fengfeng, Mingxi Zhang, Jin Wang, Yongfeng Cai, Dushao Zhao, Mingyue Guo, Luyi Wang, and Yi Shen. "Study on photocatalytic activity based on different pH values of AgBr/Ag2CO3 heterojunction." International Journal of Materials Research 111, no. 10 (October 1, 2020): 842–48. http://dx.doi.org/10.1515/ijmr-2020-1111008.

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Abstract In this work, we fabricate a highly efficient photocatalytic AgBr/Ag2CO3 heterojunction through the co-precipitation method. The obtained samples were characterized by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet-visible diffuse reflectance spectra and X-ray photoelectron spectroscopy. The photocatalytic activities of obtained samples can be assessed by visible light (λ ≥ 400 nm) degradation of rhodamine B solution. X-ray diffraction revealed that the crystallinity of the AgBr/Ag2CO3heterojunction was significantly higher than pure AgBr and Ag2CO3. Moreover, the AgBr/ Ag2CO3 heterojunction prepared at pH = 6 has the best photocatalytic performance, it can raise the degradation degree of rhodamine B over 95% at 20 min. Finally, a possible photocatalytic mechanism is discussed.

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26

Kaur, Manmeet, Shovit Bhattacharya, Vibha Saxena, D. K. Aswal, Mainak Roy, S. K. Deshpande, and S. K. Gupta. "Growth, Characterization and Gas Sensing Properties of Nanotetrapod ZnO." Journal of Nanoscience and Nanotechnology 8, no. 8 (August 1, 2008): 4106–10. http://dx.doi.org/10.1166/jnn.2008.an45.

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ZnO nanotetrapods have been obtained in large quantities by carbothermal reduction of ZnO powder. These were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, UV-visible spectroscopy and photoluminescence. Electron microscopy revealed that the overall size of the tetrapods is 1.5–2 μm and legs are 30–50 nm in diameter. The size of tetrapods as well as diameter of the legs was found to increase with deposition temperature. Photoluminescence spectra revealed that green emission originating from oxygen vacancies overwhelmed that of the near-band-edge ultraviolet peak. A band gap of 3.27 eV was calculated from optical absorption spectra which agreed well with that estimated from PL spectra. Gas sensing properties of tetrapods were investigated and these were found to be 5 times more sensitive to H2S gas at room temperature in comparison to ZnO bulk polycrystalline material.

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27

Qian, Xian Hua, Da Feng Zhang, and Xi Peng Pu. "Combustion Synthesis and Luminescence Properties of NaY_1-XTb_X(WO₄)₂ Novel Green Phosphors." Advanced Materials Research 295-297 (July 2011): 861–64. http://dx.doi.org/10.4028/www.scientific.net/amr.295-297.861.

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NaY1-xTbx(WO4)2 green phosphors have been synthesized by a facile combustion method. The structure, morphology and luminescence properties of as-synthesized phosphors were characterized via X-ray powder diffraction (XRD), photoluminescence spectra, and decay curve. The XRD results indicate that as-synthesized phosphors exhibit sheelite-type structure without any impurity phase. The as-obtained phosphors emit strong green light centered at 546 nm under ultraviolet light excitation. The lifetimes are about 0.57 ms. The excellent luminescence properties make it a new promising green phosphor for fluorescent lamps application.

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Wang, Hai Ping. "Enhancement of Ultraviolet Emission of ZnO Hollow Nanofibers." Advanced Materials Research 971-973 (June 2014): 244–48. http://dx.doi.org/10.4028/www.scientific.net/amr.971-973.244.

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ZnO hollow nanofibers were fabricated by sputtering using electrospun PVP nanofibers as templates. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction and UV Raman were used to characterize the morphologies, crystal configuration and bonding structure of ZnO hollow nanofibers. A reactive mechanism of the transformation from poor polycrystalline ZnO (Zn-rich) prepared by sputtering from a metallic Zn target to good polycrystalline ZnO after annealing is proposed. The mechanism results in great decrease of oxygen vacancies and interstitial zinc of the ZnO hollow nanofibers after annealing. Optical properties were investigated by the photoluminescence spectra. Enhancement of ultraviolet emission of the ZnO hollow nanofibers is discussed.

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Kuroki, Yuichiro, Tomoichiro Okamoto, and Masasuke Takata. "Synthesis and Luminescence Properties of Chalcopyrite-Type CuAlS₂." Key Engineering Materials 301 (January 2006): 177–80. http://dx.doi.org/10.4028/www.scientific.net/kem.301.177.

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Copper aluminum disulfide (CuAlS2) powders were synthesized in an evacuated ampoule at elevated temperatures. X-ray diffraction analysis revealed that the powders heated at temperatures higher than 800oC were single-phase CuAlS2. In the cathodoluminescence (CL) spectra measured at room temperature, the powders heated at temperatures higher than 600oC exhibited a visible emission peak at approximately 1.8 eV and a distinct ultraviolet emission peak at 3.45 eV. The powder heated at 700oC showed the maximum intensity of ultraviolet emission which is considered to be associated with excitons.

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Zuo, Jing Sheng, Chang Ping Wei, Chun Jia Peng, Rui Ying He, and Guo Dong Wang. "Preparation and Properties Characterization of N-Doped TiO₂ Film." Materials Science Forum 809-810 (December 2014): 573–77. http://dx.doi.org/10.4028/www.scientific.net/msf.809-810.573.

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Nitrogen-doped nanoTiO2 sol was prepared by sol-gel method. The obtained sol was coated onto glass substrates by spin coating method, followed by drying at low temperature and calcined at high temperature. The films were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and ultraviolet-visible spectra (UV-Vis) . The XRD spectra showed that the crystal type of N-doped TiO2 films was anatase. The SEM images showed that the surface of films were flat without obvious crack and average diameter was about 20 nm. The UV-Vis spectra showed that the absorbance of N-doped TiO2 films at ultraviolet region increased. N-doping caused photocatalysis response wavelength to turn longer. The photocatalytic activity of N-doped TiO2 films was researched through the degradation experiment of methyl orange under ultraviolet light. Higher photocatalytic degradation efficiency was exhibited compared to the pure TiO2 films.

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31

Band, D. L., and M. A. Malkan. "Combined Accretion Disk and Nonthermal Source Model for AGN." Symposium - International Astronomical Union 134 (1989): 253–54. http://dx.doi.org/10.1017/s0074180900140963.

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We model the infrared through gamma ray AGN spectrum with a combined accretion disk and nonthermal source model and fit the spectra of a number of sources. The accretion disk model of Sun and Malkan (Sun 1987) adds relativistic effects to the emission from an optically thick, geometrically thin accretion disk; further details can be found in Sun and Malkan (1988) in these proceedings. In the nonthermal source model of Band and Grindlay (1986) relativistic electrons radiate the infrared continuum by synchrotron emission, and the X-ray spectrum by inverse Compton scattering of ultraviolet photons from the accretion disk. The electron distribution consists of a flat (n ∝ γ∼−2.4) low-energy component, and a steeper (n ∝ γ∼−3.4) high-energy component.

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32

TOUFIQ, ARBAB MOHAMMAD, FENGPING WANG, QURAT-UL-AIN JAVED, QUANSHUI LI, and YAN LI. "PHOTOLUMINESCENCE SPECTRA AND MAGNETIC PROPERTIES OF HYDROTHERMALLY SYNTHESIZED MnO2 NANORODS." Modern Physics Letters B 27, no. 29 (November 15, 2013): 1350211. http://dx.doi.org/10.1142/s0217984913502114.

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In this paper, single crystalline tetragonal MnO 2 nanorods have been synthesized by a simple hydrothermal method using MnSO 4⋅ H 2 O and Na 2 S 2 O 8 as precursors. The crystalline phase, morphology, particle sizes and component of the as-prepared nanomaterial were characterized by employing X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and energy-dispersive X-ray spectroscopy (EDS). The photoluminescence (PL) emission spectrum of MnO 2 nanorods at room temperature exhibited a strong ultraviolet (UV) emission band at 380 nm, a prominent blue emission peak at 453 nm as well as a weak defect related green emission at 553 nm. Magnetization (M) as a function of applied magnetic field (H) curve showed that MnO 2 nanowires exhibited a superparamagnetic behavior at room temperature which shows the promise of synthesized MnO 2 nanorods for applications in ferrofluids and the contrast agents for magnetic resonance imaging. The magnetization versus temperature curve of the as-obtained MnO 2 nanorods shows that the Néel transition temperature is 94 K.

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Selot, Anupam, Kapil Dev, Mahendra Aynyas, and Sanjay Bhatt. "Luminescence Properties of Rare Earth Activated Aluminates Based Phosphor." Journal of Metastable and Nanocrystalline Materials 28 (December 2016): 115–19. http://dx.doi.org/10.4028/www.scientific.net/jmnm.28.115.

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A blue emitting phosphor BaAl2O4 doped with Gd3+ were prepared by combustion method at 5000C. The prepared phosphor were investigated by X-ray Diffraction to determine the crystalinity. Photoluminescence emission spectra centred at 369 nm under ultraviolet region, which corresponds to 5d-4f transition of Gd3+ ions. The PL spectra showed strong emission peak intensity and extending to 400nm to 453nm.Concentration quenching mechanism were occurred about 1mol% of Gd3+ ion. The results revealed that phosphor prepared by using combustion method can be useful WLED.

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Sun, Yangyang, Xuefeng Qian, Jie Yin, Junchao Huang, Xiaodong Ma, and Zikang Zhu. "Preparation and characterization of nanocrystalline PbSe in poly(acrylic acid-co-styrene)." Journal of Materials Research 16, no. 10 (October 2001): 2922–27. http://dx.doi.org/10.1557/jmr.2001.0401.

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The in situ reduction method was used to prepare nanocrystalline PbSe in a poly(acrylic acid-co-styrene) matrix. Metal precursor-doped polymer film was treated with selenium and reducing reagent (NaBH4) in ethylenediamine, leading to the formation of assemblies of crystalline semiconductive PbSe in polymer. The preparation was done at room temperature and ambient pressure. X-ray diffraction, x-ray photoelectron spectroscopy, infrared, scanning electron microscopy, transmission electron microscopy, and ultraviolet-visible spectra were used to characterize the as-prepared materials. The key factor for successful preparation of this composite was also discussed.

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35

WEI, XIAN QI, and BAO-YUAN MAN. "DEPENDENCE OF TEMPERATURE ON THE STRUCTURE AND PHOTOLUMINESCENCE OF ZnO THIN FILMS FABRICATED BY PULSED Nd:YAG LASER DEPOSITION ON SAPPHIRE SUBSTRATES." International Journal of Modern Physics B 21, no. 11 (April 30, 2007): 1851–60. http://dx.doi.org/10.1142/s0217979207037090.

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Zinc oxide ( ZnO ) thin films were grown on sapphire substrates at different deposition temperatures by pulsed laser deposition (PLD). The structure, composition and optical properties of deposited thin films have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), Raman and photoluminescence (PL) spectra. The results show that the ZnO thin films deposited at 500°C have the best crystalline quality with hexagonal structure, surface morphology and stoichiometric composition. The PL spectrum reveals that the sample possesses the strongest ultraviolet (UV) emission at 370 nm and the weakest blue emission at 459 nm under this condition. Raman spectra and weak blue emission of PL spectra show that very few oxygen vacancies exist in the ZnO thin films.

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Koratkar, Anuradha. "Are LINERs Starbursts or Mini-quasars? A Comparative Study of their Ultraviolet Spectra." Symposium - International Astronomical Union 194 (1999): 71–74. http://dx.doi.org/10.1017/s0074180900161741.

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Low Ionization Nuclear Emission Line Regions (LINERs) are found in ˜30% of all bright galaxies. The nuclear luminosities in these objects are such that they can be produced by a number of mechanisms and there have been heated debates on the nature of ionizing sources in LINERs. The variety of ionizing mechanisms suggested are low luminosity AGNs, starbursts, shocks, or any combination of these. We have studied Hubble Space Telescope (HST) ultraviolet (UV) spectra of seven LINERs having compact nuclear UV sources.The picture emerging from this comparison is that the compact source observed in these LINER galaxies, at least in some cases, is a nuclear star cluster rather than a low-luminosity active galactic nucleus (AGN). In these cases, the UV luminosity is driven by tens of thousands of O-type stars, depending on the assumed extinction for these objects. The O-stars could be the high-mass end of a bound stellar population, similar to those seen in super star clusters. Our data do not exclude the possibility that a similar stellar continuum source could dominate in all the LINERs. Alternatively, there may be two types of UV-bright LINERs: those where the UV continuum is produced by a starburst, and those where it is nonstellar.The “clearly-stellar”, weak [O I] emitters, LINERs have relatively weak X-ray emission, and their stellar populations probably provide enough ionizing photons to explain the observed optical emission-line flux. The other LINERs, strong [O I] emitters, have severe ionizing photon deficits, for reasonable extrapolations of their UV spectra beyond the Lyman limit, but have an X-ray/UV power ratio that is higher by two orders of magnitudes than that of the “clearly-stellar” LINERs. A component which emits primarily in the extreme-UV may be the main photoionizing agent in these objects.Recent results show that nuclear-starburst and quasar-like activity are often intermingled. Our results extend this result to the lower luminosities of the LINERs.

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37

Zhao, Shihua. "Effect of Different Excitation Wavelengths on Luminescent Properties of ZnO/Anodic Alumina Membrane (AAM) Arrays." Nanoscience and Nanotechnology Letters 10, no. 3 (March 1, 2018): 409–12. http://dx.doi.org/10.1166/nnl.2018.2632.

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ZnO/AAM (anodic alumina membrane) arrays were prepared by an electrodeposition method and X-ray diffraction (XRD) patterns show that the characteristic diffraction peaks of ZnO appear, such as the lattice planes of (100), (002), and (102), moreover, the diffraction peaks of Al2O3 are dominated. Scanning electron microscopy (SEM) images show that the average sizes of the ZnO particles are about 100 nm corresponding to the channel diameters of AAM, and the ZnO arrays are composed of those close particles linked together. The photoluminescence emission spectra express that the as-prepared ZnO arrays can give out relatively pure ultraviolet light (395 nm) from the excitons.

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38

Dong, Pengyu, Yan Hao, Peiyang Gao, Entian Cui, and Qinfang Zhang. "Synthesis and Photocatalytic Activity of Ag3PO4Triangular Prism." Journal of Nanomaterials 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/857506.

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Ag3PO4triangular prism was synthesized by a facile chemical precipitation approach by simply adjusting external ultrasonic condition. The as-synthesized Ag3PO4triangular prism was characterized by X-ray diffraction pattern (XRD), field emission scanning electron microscopy (SEM), fourier transform infrared (FTIR) spectra, and ultraviolet-visible diffuse reflectance (UV-vis DRS) absorption spectra. The photocatalytic activity of Ag3PO4triangular prism was evaluated by photodegradation of organic methylene blue (MB), rhodamine B (RhB), and phenol under visible light irradiation. Results showed that Ag3PO4triangular prism exhibited higher photocatalytic activity than N-doped TiO2and commercial TiO2(P25) under visible light irradiation.

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39

Zhang, Jiao, Yanmin Yang, Fang Yu, Yanzhou Liu, Boning Han, Chao Mi, and Linlin Liu. "Synthesis and Luminescence Properties of La2W2O9:Eu3+ Micron-Crystals." Journal of Nanoscience and Nanotechnology 16, no. 4 (April 1, 2016): 3852–56. http://dx.doi.org/10.1166/jnn.2016.11791.

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La2W2O9:2%Eu3+ phosphors were synthesized by a typical hydrothermal procedure. The samples were characterized by X-ray diffraction and scanning electron microscope (SEM). X-ray diffraction analysis showed that a stock solution pH value equal to 9 is the ideal value, while the crystallization of the hydroxyl sodium yttrium tungstate crystal is improved by increasing the PH values of stock solution within limits. Meanwhile, SEMs of different pH values were recorded. Additionally, photoluminescence excitation (PLE) and emission (PL) spectra were measured. It was found that this phosphor can be effectively excited by C–T band (266 nm) and ultraviolet light 342 nm. The wavelengths at 342 nm fit in nicely with the whole visible region, thus the La2W2O9:2%Eu3+ phosphors emit white light. Furthermore, the annealing temperature’s impact on PLE and PL spectra was also studied. The Eu3+-doped La2W2O9 phosphor may be a better candidate than current method for solid-state lighting applications.

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40

Picqué, Nathalie, and Theodor W. Hänsch. "Photon-level broadband spectroscopy and interferometry with two frequency combs." Proceedings of the National Academy of Sciences 117, no. 43 (October 14, 2020): 26688–91. http://dx.doi.org/10.1073/pnas.2010878117.

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We probe complex optical spectra at high resolution over a broad span in almost complete darkness. Using a single photon-counting detector at light power levels that are a billion times weaker than commonly employed, we observe interferences in the counting statistics with two separate mode-locked femtosecond lasers of slightly different repetition frequencies, each emitting a comb of evenly spaced spectral lines over a wide spectral span. Unique advantages of the emerging technique of dual-comb spectroscopy, such as multiplex data acquisition with many comb lines, potential very high resolution, and calibration of the frequency scale with an atomic clock, can thus be maintained for scenarios where only few detectable photons can be expected. Prospects include spectroscopy of weak scattered light over long distances, fluorescence spectroscopy of single trapped atoms or molecules, or studies in the extreme-ultraviolet or even soft–X-ray region with comb sources of low photon yield. Our approach defies intuitive interpretations in a picture of photons that exist before detection.

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41

Kumar, Vijendra, R. K. Shukla, and Jyoti Shakya. "Effect of Ultraviolet Irradiation on Photo-Physical and Surface Electronic Properties of MoS2." Journal of Nanoscience and Nanotechnology 20, no. 10 (October 1, 2020): 6500–6504. http://dx.doi.org/10.1166/jnn.2020.18581.

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In this study, exfoliation of molybdenum disulfide (MoS2) using the chemical exfoliation method was successfully achieved via probe sonication followed by centrifugation. The observed ultravioletvisible (UV-Vis) spectra of the MoS2 dispersions indicated the presence of a few layers of MoS2. The morphological, structural, optical and surface electronic properties before and after UV light irradiation were investigated by the technique of X-ray diffraction, the Raman spectroscopic measurements, transmission electron microscopy (TEM), and the scanning Kelvin probe microscopy (SKPM). It was observed that after UV irradiation, the Fermi level moves towards the valence band.

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42

Wang, Jian, Hui Feng Li, Yun Hua Huang, and Yue Zhang. "Fabrication and Optical Properties of Mn-Doped ZnO Nanowires." Advanced Materials Research 79-82 (August 2009): 453–56. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.453.

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Mn-doped ZnO nanowires were successfully synthesized on silicon substrate by chemical vapor deposition method with Au catalyst. The X-ray diffraction (XRD) pattern indicates that the Mn-doped ZnO nanowires are hexagonal wurtzite structure and no second phase. The X-ray spectroscopy (EDX) and X-ray photoelectron spectrum (XPS) spectra exhibited the Mn ions were induced into the ZnO nanowires. Photoluminescence (PL) spectra were excited by 325 nm Xe lamp laser. Three peaks are observed in Mn-doped ZnO nanowires, two ultraviolet (UV) emissions at 370 nm and 386 nm, a visible emission at 405 nm. The emission at 405 nm is first found in Mn-doped ZnO nanowires that attributed to the electron transition from bottom of the conduction band to zinc vacancy defect energy level. The existence of Mn element changes the optical property of the ZnO nanowires.

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43

Guan, Zi-Sheng, Xin-Tong Zhang, Ying Ma, Ya-An Cao, and Jian-Nian Yao. "Photocatalytic activity of TiO2prepared at low temperature by a photo-assisted sol-gel method." Journal of Materials Research 16, no. 4 (April 2001): 907–9. http://dx.doi.org/10.1557/jmr.2001.0128.

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TiO2nanocrystals were prepared by a photo-assisted sol-gel process in which tetrabutoxide titanate was hydrolyzed in acidic medium under ultraviolet irradiation. X-ray diffraction and Raman spectra showed that the as-prepared TiO2particles without further annealing were well-crystallized anatase. Such TiO2particles were easily immobilized on dacron cloth and showed very high photocatalytic activity. In contrast, TiO2particles were ill crystallized and showed lower activity when no light was introduced under otherwise equal conditions.

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Huang, Jun, Xiao Jing Lv, Mi Ouyang, Bin Hu, and Cheng Zhang. "Atmospheric Pressure Synthesis of ZnO Nanotubes by Aqueous Solution Route." Advanced Materials Research 669 (March 2013): 189–93. http://dx.doi.org/10.4028/www.scientific.net/amr.669.189.

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Single-crystalline ZnO nanotubes were fabricated via a simple aqueous solution method under low temperature and atmospheric pressure conditions. X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) equipped with the selected area electron diffraction (SAED) setup were used to analyze the crystal structure, surface morphology and inner structure of ZnO nanotubes. Photoluminescence (PL) and UV-visible absorption spectra were carried out to investigate optical properties of ZnO nanotubes. The results indicate ZnO nanotubes only exhibit sharp and strong near ultraviolet emission at 363 nm according to PL spectrum.

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Tao, Tingxian, Jiabin Xu, Hui Song, Rongmei Liu, and Zhichuan Wu. "Ag/Tio2/AOF as an Easily Reused and Highly Active Catalyst for Dye Photo-Degradation." Journal of Engineered Fibers and Fabrics 11, no. 1 (March 2016): 155892501601100. http://dx.doi.org/10.1177/155892501601100108.

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A novel TiO2 loaded with Ag photocatalyst covering on a modified fiber surface was prepared by coordination-hydrolysis combined with a photo-reduction process. Samples were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscope (SEM), X-ray photoelectron spectroscope (XPS) and ultraviolet visible diffuse reflectance spectra (UV-vis DRS). Compared with powder TiO2, the TiO2/amidoxime fiber (TiO2/AOF) and Ag/TiO2/amidoxime fiber (Ag/TiO2/AOF) exhibited a significant absorption edge of red-shift from ultraviolet to visible light region. The samples’ visible-light photodegradation activities were investigated and the results showed that the Ag/TiO2/AOFs exhibit excellent photocatalytic activities-about 99% decomposition rate of Rhodamine B with 100 minutes of visible light irradiation. The catalyst exhibits excellent catalytic activity and is easily recovered and reused.

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Kaastra, J. S., M. Mehdipour, E. Behar, S. Bianchi, G. Branduardi-Raymont, L. Brenneman, M. Cappi, et al. "Recurring obscuration in NGC 3783." Astronomy & Astrophysics 619 (November 2018): A112. http://dx.doi.org/10.1051/0004-6361/201832629.

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Context. Obscuration of the continuum emission from active galactic nuclei by streams of gas with relatively high velocity (>1000 km s−1) and column density (>3 × 1025 m−2) has been seen in a few Seyfert galaxies. This obscuration has a transient nature. In December 2016 we witnessed such an event in NGC 3783. Aims. The frequency and duration of these obscuration events is poorly known. Here we study archival data of NGC 3783 in order to constrain this duty cycle. Methods. We use archival Chandra/NuSTAR spectra taken in August 2016. We also study the hardness ratio of all Swift XRT spectra taken between 2008 and 2017. Results. In August 2016, NGC 3783 also showed evidence of obscuration. While the column density of the obscuring material is ten times lower than in December 2016, the opacity is still sufficient to block a significant fraction of the ionising X-ray and extreme ultraviolet photons. From the Swift hardness ratio behaviour we find several other epochs with obscuration. Obscuration with columns >1026 m−2 may take place about half of the time. Also, in archival X-ray data taken by the Advanced Satellite for Cosmology and Astrophysics (ASCA) in 1993 and 1996 we find evidence of obscuration. Conclusions. Obscuration of the ionising photons in NGC 3783 occurs more frequently than previously thought. This may not always have been recognised due to low-spectral-resolution observations, overly limited spectral bandwidth or confusion with underlying continuum variations.

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Trujillo Villanueva, Luis Eduardo, Felipe Legorreta García, Fidel Pérez Moreno, Marius Ramírez Cardona, and Edgar Arturo Chávez Urbiola. "Ultraviolet Light Effects on Cobalt–Thiourea Complexes Crystallization." Crystals 11, no. 5 (April 23, 2021): 473. http://dx.doi.org/10.3390/cryst11050473.

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In this work, a cobalt–thiourea complexes crystal synthesis was carried out comparatively with and without ultraviolet light assistance (λ = 253 nm), and its effect was studied. Through the solvent evaporation technique, crystalline forms were obtained, which were analyzed and characterized by different techniques: Raman spectroscopy, X-ray diffraction (XRD), and digital optical microscopy. Crystal’s shape changes were observed when comparing those obtained from the solution with and without ultraviolet (UV) assistance. It was found that the UV light effect on the crystals causes a structural modification of the complex synthesized in the (022) (120) planes and without UV assistance in the (002), (111), (131¯), and (132¯) planes. It is also possible to observe an increase in intensity by Raman spectra identified as Co–S bonds (297 cm−1) for crystals synthesized with UV assistance.

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Xu, Song Ning, Z. Q. Cai, N. K. Sun, Y. B. Gao, and F. Liu. "Optical Properties of Co-Doped Zno Nano Powder Material Prepared by Ball Milling." Applied Mechanics and Materials 143-144 (December 2011): 190–93. http://dx.doi.org/10.4028/www.scientific.net/amm.143-144.190.

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Zn1-xCoxO nano powders have been successfully prepared by ball milling and have been annealing at 600°C. The crystal structure and optical properties of sample were characterized by X-ray diffraction (XRD), photoluminescence spectra (PL) and ultraviolet visible light absorption spectra (UV), and the formation mechanism was discussed. Co-doped ZnO nano powders exhibit wurtzite (hexagonal) structure. Co2+enters into ZnO crystal structure and substitutes for Zn2+. All samples show typical luminescence behavior with about 396nm UV emission peak. In addition, the about 450nm and 470nm blue emission peaks are found in photoluminescence spectra. Before the doped content is within 8at%, the band edge of ultraviolet absorption appears red shift phenomenon with the increase of doping content. The peak position was shifted from 362nm (3.43eV) to 367nm (3.38eV). Annealing is in favor of the replacement that Co2+enters into ZnO crystal structure and substitutes for Zn2+

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Lv, Zhi Yong, Yue Zhao, Zhao Li, Xiao Yan Liang, Zhan Jie Hou, Lin Jun Wang, and Jia Hua Min. "Photoluminescence and Raman Scattering of Cu-N Codoped ZnO Thin Films." Applied Mechanics and Materials 110-116 (October 2011): 565–70. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.565.

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Polycrystalline ZnO thin films codoped with Cu and N have been obtained by chemical bath deposition. The effect of N incorporation and Cu-N incorporation on microstructure and optical properties of ZnO films has been investigated. X-ray diffraction patterns of the films indicated N incorporation deteriorated the crystalline quality while Cu-N incorporation improved the crystalline quality. The PL spectra showed that the relative intensity between the ultraviolet luminescence and the deep level-center luminescence of ZnO thin films was clearly correlated with the crystalline quality. Furthermore, the Raman spectra revealed the intensity of E2(high) increase with Cu-N incorporation.

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Guo, Shu Xia, and Ji Wu Li. "Mg-Induced Shift of Band Edge in ZnO:Mg Probed by the Visible Luminescence." Advanced Materials Research 590 (November 2012): 73–78. http://dx.doi.org/10.4028/www.scientific.net/amr.590.73.

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Abstract:

Mg-doped ZnO was synthesized using a co-precipitation technique. X-ray diffraction (XRD) measurements and absorption spectra show that Mg ions are doped into the lattice positions of ZnO. In the room temperature photoluminescence (PL) spectra, two emission bands, ultraviolet (UV) and visible, were observed. Either of two emissions shows a blue-shift. The visible emission band is composed of the green emission and the blue emission. The amount of blue-shift in green emission is 0.03 eV, about half of the amount of blue-shift in blue emission. Mg substitution raises and lowers conduction- and valence-band edges, respectively.

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Journal articles on the topic 'Ultraviolet spectra, Photons, X-ray diffraction'

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