Photoluminescence, with

The [Au2(dcpm)2]X2 complexes (X = C104, PF ", Cp3S03, Au(CN)2 ) display intense photoluminescence with Amax at 360-368 nm in the solid state at room temperature and in glassy solutions at 77 K. Solid samples of [Au2(dcpm)2](C104)2 and [Au2(dcpm)2](PF6)2 individually display a weak visible emission at Xmax= 564 and 505 nm, respectively, but a similar emission is not detected for [Au2(dcpm)2]... 

The optical reflectance spectra were dependent on the nanocrystallite structure and dimensions, porosity and the layer thickness (Fig. 9.2). The maximal photosensitivity in the visible wavelength range of the spectra (30-35 mA/Lm) was typical of the sNPS layers with the nanocrystallite dimensions of 15 nm, and it decreased with increasing size of the nanocrystallites. The maximal sensitivity to the ultraviolet irradiation was obtained for sNPS layers with nanocrystalhte dimensions of 20-25 nm. sNPS layers obtained by electrochemical etching as well as by chemical etching showed the photoluminescence typical of this material a broad peak in the visible spectrum with the intensity sufficient for observation of the photoluminescence with a naked eye. sNPS samples obtained by chemical or electrochemical etching had intensive emission with the maximum at A, 640 nm and 700 nm. 

Based on those propositions mentioned above, we tried to design a mesoporous material having micro crystalline wall by controlling the ratio of Q4 silicate species formed around TPA and Q2,3 silicate species interact with the micelles. To synthesize micro-mesoporous composite material through the control of Q2-3 and Q4 groups, two different templates were used and nucleation step of microporous material was introduced prior to the crystallization. And also we have attempted to monitor microenvironment of micro-mesoporous composite materials during the nucleation and crystallization steps using TG-DTA and photoluminescence with pyrene probe. 

ZrPV(X) compounds also exhibited photoluminescence, with a maximum around 340 nm, upon irradiation at 285 nm. The excitation curves and the luminescence lifetimes of all the three materials were similar, and the magnitude of the lifetime (20 ns) suggested that the emission originates from the singlet state. These results, in many aspects, were consistent with that observed with methylviologen intercalated into clays [90],... 

A soluble silole-containing polyplatinayne 51 was prepared.47 As compared to 2,5-dibromo-l,l-diethylsilole (Xmax = 326 nm), the positions of the low-lying shoulder bands (Xmax = 504 nm in CH2C12) are remarkably red-shifted by 178 nm for 51 after the inclusion of heavy-metal chromophores. This is possibly due to the intramolecular D-A interaction between the electron-rich metal ethynyl unit and the electron-poor silole ring. The Ee value is impressive at 2.10 eV for 51, and it is significantly lowered by 1.0 eV relative to 53 (3.10 eV).48 Compound 51 is photoluminescent with the singlet emission band at 537 nm. No room temperature emission from the Ti state was detected over the measured spectral window. 

Such bilayers were studied by photoluminescence, with a view to extracting the degree of photoluminescence quenching induced by a thin acceptor layer on the polymer [18]. Studies of photoluminescence quenching in bilayers have corroborated the picture derived from studies of photoelectrical performance. The short exciton diffusion length in PEOPT is 5 nm, consistent with both PL quenching and photodiode performance. 

The situation is somewhat more complicated in two-dimensional polysilanes, which have intermediate properties between the one-dimensional chain-like polysilanes and three-dimensional bulk silicon. The gap is of a quasi-direct nature as the indirect gap is only slightly smaller than the direct one [11]. However, the excitons strongly bind to the lattice which results in a large Stokes shift of the PL [26]. The observed blue shift of the absorption and photoluminescence with decreasing size of the polysilanes is considered to be due to confinement effects of the excitons [12,26]. The strong coupling of the exciton to the lattice decreases somewhat the blue shifts as compared with the linear chains, and it results in a stronger localization of the exciton over a smaller number of Si atoms [12,26]. 

This review deals with the applications of photolurainescence techniques to the study of solid surfaces in relation to their properties in adsorption, catalysis, and photocatalysis, After a short introduction, the review presents the basic principles of photolumines-cence spectrosajpy in relation to the definitions of fluorescence and phosphorescence. Next, we discuss the practical aspects of static and dynamic photoluminescence with emphasis on the spectral parameters used to identify the photoluminescent sites. In Section IV, which is the core of the review, we discuss the identification of the surface sites and the following coordination chemistry of ions at the surface of alkaline-earth and zirconium oxides, energy and electron transfer processes, photoluminesccncc and local structure of grafted vanadium oxide, and photoluniinescence of various oxide-... 

As shown in Fig. 19, vanadium oxide supported on Vycor glass exhibits a photoluminescence spectrum at about 400-600 nm upon excitation of the absorption band at about 320 nm (33, 34, 63, 69,115,116). The absorption and photoluminescence spectra are represented by Eq. (12). The addition of 62, CO, N2O, C2H4, CsHg, or QHjj to the catalyst led to the quenching of the photoluminescence with differing efficiencies but without any changes in the shape of the spectrum. 

The addition of O2 onto the anchored titanium oxide catalyst led to an efficient quenching of the photoluminescence at 77 K. The addition of N2O also led to the quenching of the photoluminescence with an efficiency lower than that of O2. Such an efficient quenching of the photoluminescence by the addition of O2 or N2O is expected when the emitting sites are dispersed on the support surfaces due to the efficient interaction of the emitting sites with the quencher molecules 168, 212). 

Figure 2 also shows that the addition of NO, H2O or CO2 molecules onto the Ti-MCM-48 catalyst leads to an efficient quenching of the photoluminescence as well as a shortening of the lifetime of the char transfer excited state, its extent depending on the amount of gasses added. Such an efficient quenching of the photoluminescence with NO, CO2 or H2O molecules... 

During the last few years, we have studied silicon nanocrystals produced by CO2 laser pyrolysis of silane and we have been able to show that, in these experiments, the PL characteristics can be unambiguously explained in terms of quantum confinement effects.However, to observe the photoluminescence with the naked eye, we had to wait a few hours or even a few days. It appeared that the silicon nanocrystals were passivated by natural aerial oxidation and that, with time, the photoluminescence became more and more intense. 

CuInSe2XTe2(i-x) nanoparticles incorporated into silicate glass reveal complicated photoluminescence with the above-than-band gap excitation. It depends on composition of nanoparticles. The secondary heat treatment differently affects the selenides and tellurides. Defect states within the particles and excitons are proposed as possible sources of the luminescence. 

The new type of star molecules constructed in this fashion are now also attractive as blue luminophores as active component in LEDs, in particular also because of their ability to be worked into transparent, amorphous films. The quaterphenyl derivative 26 shows, for example, a long wavelength absorption maximum at 314 nm, and an intensive blue photoluminescence with an emission maximum at 401 nm (Fig. 7). 

Polyhydrazides and poly(amide-hydrazide)s with redox-active carbazole and triphenylamine units have been synthesized [49]. The resulting poly( 1,3,4-oxadiazole)s andpoly(amide-l,3,4-oxadiazole)s show high glass transition temperatures of 288-330 °C and a high thermal stability. The polymers show a weak to medium photoluminescence with emission maxima of 474-506 nm. In addition, the materials show an enhanced redox stability and electrochromic performance. 

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