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The time-dependent density functional theory (DFT) approach is employed to explain the structure, as well as the optical properties of the phosphorescent platinum compounds. The interligand [pi]-[pi] interactions are shown to play an extremely significant role in determining the geometry and energy lowering in the triplet excimer formation in these phosphors.

The photoluminescence phenomena of [Ce.sup.3+]-doped [Y.sub.3][Al.sub.5][O.sub.12] nanophosphors are examined and compared with bulk phosphors. The photoionization effect is observed for the nanophosphors where the 5d electrons are lost to the conduction band and trapped at the surface-defective sites.

CdS/PAM nanocomposites were successfully synthesized in situ through an ultrasound-assisted route under ambient condition. The CdS/PAM nanocomposites had a stronger ability to promote electron transfers between Hb and the Au electrode than CdS nanoparticles prepared under the same conditions and there are distinct differences in the photoluminescence and UV-vis spectra of the pure CdS and CdS/PAM nanocomposites.

Y(sub 2)O(sub 3): Eu(super 3+) and Y(sub 1.35)Gd(sub 0.6)O(sub 3): Eu(super 3+) luminescent thin films were grown on Al(sub 2)O(sub 3) (0001) and Si(100) substrates by a pulsed layer deposition technique. The improved brightness of Y(sub 1.35)Gd(sub 0.6)O(sub 3): Eu(super 3+) films may result from not only improved crystallinity leading to higher oscillating strengths for the optical transitions, but also reduced internal reflections caused by rough surfaces and increased UV-solid volume due to increased effective radiation area.

The study shows that the inclusion of Tb(super 3+) ion doped into the storage phosphor BaFBr:Eu(super 2+) resulted in an increased purity of the host material as well as an improvement in the linearity of the photostimulated luminescence (PSL) intensity versus the x-ray irradiation dose. These results can be explained by considering the reduction of impurity Eu(super 3+) ion following trapping of the photoexcited electrons.