Photoluminescence studies, high

An important aspect of semiconductor films in general with regard to electronic properties is the effect of intrabandgap states, and particularly surface states, on these properties. Surface states are electronic states in the forbidden gap that exist because the perfect periodicity of the semiconductor crystal, on which band theory is based, is broken at the surface. Change of chemistry due to bonding of various adsorbates at the surface is often an important factor in this respect. For CD semiconductor films, which are usually nanocrystalline, the surface-to-volume ratio may be very high (several tens of percent of all the atoms may be situated at the surface for 5 mn crystals), and the effects of such surface states are expected to be particularly high. Some aspects of surface states probed by photoluminescence studies are discussed in the previous section. 

In the present study, highly dispersed titanium oxides included within the zeolite cavities (Ti-oxide/Y-zeolite) and framework (Ti-MCM-41,-48) were prepared using an ion-exchange method and hydrothermal synthesis to be used as photocatalysts for the reduction of CO2 with H2O at 328 K. The characterization of these catalysts by means of in situ photoluminescence, diffuse reflectance absorption, XAFS (XANES and FT-EXAFS), and ESR measurements have been carried out and special attention has been focused on the relationship between the structure of the titanium oxide species and the reaction selectivity in the photocatalytic reduction of CO2 with H2O to form CH3OH. 

Ya Zhydachevskii, Galanciak D, Kobyakov S, Berkowski M, Kaminska A, Suehoeki A, Ya Zakharko, Durygin A (2006) Photoluminescence studies of Mn" " ions in YAIO3 crystals at ambient and high pressure. J Phys Cond Matter 18 11385... 

Gryk W, Grinberg M, Joubeit M-F, Dujardin C, Grosvalet L, Pedrini C (2006) High pressure photoluminescence study of cerium-doped Lu2Si05- Optical Mater 28 115... 

Xu D et al (1999) Optical absorption and photoluminescence studies of free-standing porous sihcon films with high porosities. J Phys Chem B 103(26) 5468-5471 Xu D, Guo G, Gui L, Tang Y, Qin GS (2000) Optical absorption property of oxidized free-standing porous silicon films. Pure Appl Chem 72(l-2) 237-243 Yao S et al (2006) Electroosmotic pumps fabricated from porous sihcon membranes. J Microelectromech Syst 15(3) 717-728... 

Photoluminescence studies on rare earth titanates prepared by self-propagating high temperature synthesis method. Spectrochim. Acta. A. Mol Biomol Spectrosc., 71 (4), 1281-1285. 

A.K. Sood, K. Jayaram, D.V.S. Muthu, Raman and high-pressure photoluminescence studies on porous silicon. J. Appl. Phys. 72(10), 4963-4965 (1992)... 

Zinc sulfide, with its wide band gap of 3.66 eV, has been considered as an excellent electroluminescent (EL) material. The electroluminescence of ZnS has been used as a probe for unraveling the energetics at the ZnS/electrolyte interface and for possible application to display devices. Fan and Bard [127] examined the effect of temperature on EL of Al-doped self-activated ZnS single crystals in a persulfate-butyronitrile solution, as well as the time-resolved photoluminescence (PL) of the compound. Further [128], they investigated the PL and EL from single-crystal Mn-doped ZnS (ZnS Mn) centered at 580 nm. The PL was quenched by surface modification with U-treated poly(vinylferrocene). The effect of pH and temperature on the EL of ZnS Mn in aqueous and butyronitrile solutions upon reduction of per-oxydisulfate ion was also studied. EL of polycrystalline chemical vapor deposited (CVD) ZnS doped with Al, Cu-Al, and Mn was also observed with peaks at 430, 475, and 565 nm, respectively. High EL efficiency, comparable to that of singlecrystal ZnS, was found for the doped CVD polycrystalline ZnS. In all cases, the EL efficiency was about 0.2-0.3%. 

The preparation of ZnSe materials is an area of interest and study. The coordinating ability of the solvent used in the solvothermal synthesis of zinc selenide was demonstrated to play an important role in the nucleation and growth of nanocrystalline ZnSe.604 Thermolysis of bis [methyl( -hexyl)di-seleno]carbamato]zinc gave highly monodispersed particles characterized by electronic spectroscopy, photoluminescence, X-ray diffraction, and electron microscopy.605... 

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