Radiationless Deactivation of Low-Field Chromium Complexes in Solids.
Abstract
Thermal quenching of fluorescence is a major loss mechanism which may impede the performance of tunable solid-state lasers, but whose impact is difficult to assess a-priori. The object of the reported investigation was to achieve a quantitative understanding of the factors which control this process, with the ultimate goal of formulating design criteria for tunable solid-state laser materials. The temperature dependence of chromium photoluminescence spectra and lifetimes has been measured in ordered-perovskite (Cs2NaYC16, K2NaScF6 and K2NaGaF6) low-crystal-field host crystals. After the failure of linear-coupling models was demonstrated, a successful theoretical model was proposed in which fluorescence quenching is mediated by quadratic coupling to assymetric modes of vibration. Parameters of the model are constrained by empirical spectral information, and radiationless transition rates are calculated by numerical line-shape simulation. Both semi-empirical (INDO) and ab-initio molecular-orbital cluster calculations have been performed in conjunction with lattice-statics calculations in a continuing effort to refine this quenching model. Photoluminescence spectra and lifetimes, measured as functions of temperature and pressure in a diamond-anvil cell, revealed a pressure-induced transition from broad-band fluorescence to narrow-band phosphorescence; i.e., from low-crystal-field to high-crystal-field behavior.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 20, 1986
- Accession Number
- ADA165734
Entities
People
- Ralph H. Bartram
Organizations
- University of Connecticut