Ruby at high pressure. II. Fluorescence lifetime of theRline to 130 GPa

We have measured the ruby R-line fluorescence lifetime to 130 GPa in a nonhydrostatic environment. We observed a rapid, nonlinear increase in the lifetime with increasing pressure. The lifetime data are fitted to a theory relating the transition rate to parameters obtained independently from measurements of high-pressure ruby spectra. We discuss the R-line fluorescence intensity in terms of a rate-equation analysis of a model ruby three-level system. We conclude that the excitation mechanism of observed R-line fluorescence at very high pressures is likely to be different from the mechanism at ambient pressure.