Host Absorption Band Research Articles

Photoluminescence properties of Al 3GdB 4O 12:Eu phosphors

An investigation is reported of the photoluminescence (PL) properties of Al 3GdB 4O 12:Eu phosphors. Under vacuum ultraviolet excitation, Al 3GdB 4O 12:Eu exhibited a bright red luminescence with CIE chromaticity coordinates of (0.643, 0.356) with a PL intensity of 60% of the sodium salicylate standard. The PL spectrum showed a ground state splitting pattern consistent with D 3 symmetry. The PL excitation spectrum showed sharp lines due to the 8S 7/2– 6I J and 6P J transitions of Gd 3+ in addition to the f–f transitions of Eu 3+. The charge transfer band of Eu was observed at 250 nm and the host absorption band was detected at 157 nm. Time-resolved spectroscopy was performed to investigate the interaction between Gd and Eu ions. The energy transfer rate from Gd to Eu ions was found to be 17 000 s −1.

Optical Properties of Chemically Mixed Molecular Crystals

Abstract The substitutionally mixed crystal system of tetracene as guest in an anthracene host lattice has been reinvestigated with perturbation theory calcualations of intensity mixing. The effect of the actual misalignment of the guest molecules relative to the host lattice is appraised. Additional refinements in the calculations incorporate the higher energy host states and the initially mixed polarization of the free host and guest absorption bands. The results are compared to existing experimental data.