High-Pressure Studies of Luminescent Spectra and Lifetimes in Alkali-Halides Doped with Cu+ and Ag+

The effect of pressure to 140 kbar has been measured on the room-temperature luminescent properties of some sodium and potassium halides doped with ${\mathrm{Cu}}^{+}$ and ${\mathrm{Ag}}^{+}$. The properties studied include peak location, peak half-width, and luminescent lifetime. A signal-averaging luminescent decay apparatus is described which permits the measurement of lifetimes in the range from 50 nsec to 10 sec. The peak locations and half-widths are discussed in terms of a single-configuration coordinate model, and parameters characteristic of the potential wells are extracted. Following Kubo's picture of phonon-assisted transitions, these parameters are used to predict the change in lifetime with pressure. The agreement between experiment and calculation is reasonable. The possibilities and limitations of the analysis are discussed.