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The properties of various inorganic scintillator materials with different origin of their VUV luminescence have been studied under pulsed excitation by XUV (50-1000 eV) synchrotron radiation. A comparison of spectral and timing characteristics of these crystalline VUV emitters has been performed. The processes of energy transfer from the host crystal to the luminescence centers of different nature were analyzed from the features of excitation spectra in the regions of inner-shell absorption. Index Terms--Crossluminescence, excitous, fast VUV luminescence, inorganic scintillators, rare earth ions, synchrotron radiation.

Excitation spectra of Ca[F.sub.2], Sr[F.sub.2] and Ba[F.sub.2] crystals doped by Cd[F.sub.2], La[F.sub.3], Y[F.sub.3] in vacuum ultraviolet region were investigated at liquid-helium temperature and at room temperature. Spectra of doped Ba[F.sub.2] at low temperature and Ca[F.sub.2], Sr[F.sub.2] at room temperature show significant decrease of excitation intensity against those in undoped crystals while the intensifies in exciton regions remain nearly the same. The common reason of the suppression of exciton emission by impurity in alkaline-earth fluorides is unradiative electron-hole recombination on impurity sites. Index Terms--Excitons, impurity, suppression, vacuum ultraviolet.

Commonly used biological indicators for assessing the efficiency of decontamination procedures include the spores of Bacillus atrophaeus (BA) and Geobacillus stearothermophilus (GS). BA and GS spores emit tryptophan-like fluorescence around 320 nm when excited by 280 nm UV light. This fluorescence signal is highly dependent on vaporised hydrogen peroxide (VHP) concentration around the spores, since VHP quenches the fluorescence. In this study we investigated the precise influence of VHP concentration on the autofluorescence properties of BA and GS spores. For both types of spores, the fluorescence signal intensity was found to fall faster and to a relatively lower level when higher VHP concentration was applied. The shape of the signal fall-off as a function of time was found to be well approximated by biexponential decay functions with similar time-constants for BA and GS spores, finally resulting in the equilibrium (or plateau/residual) fluorescence intensity levels that were very different for these samples. The reasons for the fluorescence signal fall-off were investigated by spectral fluorescence signatures (SFS) of the spores. The SFS measurements of the spores during VHP decontamination revealed that the spectral maximum of tryptophan-like (Trp-like) fluorescence changes towards a smaller Stokes shift and has the intensity fall-off due to quenching and oxidation under VHP influence. [ABSTRACT FROM AUTHOR]

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A series of fluorochlorozirconate glasses doped with manganese ions is synthesized and investigated as possible red‐emitting phosphors in comparison with conventional green‐emitting fluorozirconate glasses doped with Mn2+. It is found that the replacement of fluorine by chlorine ions results in broadening and a long‐wavelength shift of the manganese luminescence band into the red region (peaked at 615 nm) although the emission spectrum still has some contribution of the green sub‐band. It turns out also that decay kinetics of luminescence from fluorochlorozirconate glasses becomes nonexponential in contrast to single‐exponential decay observed for green luminescence from Mn2+‐doped fluorozirconate glasses. The observation of two emission components in the luminescence spectrum of fluorochlorozirconate glasses is interpreted as being due to the presence of two Mn2+ emission centers in different local environments. The presence of 2+ valence states of manganese ions in both types of glasses is confirmed by recording X‐ray absorption near edge structure (XANES) spectra at Mn L2,3 edge. Substitution of F− by Cl− ions in anion sites neighboring to Mn2+, leads to a significant rearrangement of the local environment of Mn2+ ions, which results in the long‐wavelength shift of Mn2+ emission spectrum. [ABSTRACT FROM AUTHOR]