Optical dephasing by nonequilibrium phonons in LaF3

Phonon-induced coherence loss (PICL) is produced by a monoenergetic nonequilibrium distribution of phonons in LaF3+. The phonons are generated by relaxation between excited states of the Pr3+ ion after selective excitation with a pulsed, tunable dye laser. The optical dephasing is observed from the effect on the free-induction decay of Pr3+ ions whose excited-state level separation is resonant with the phonons. It is shown that PICL is a sensitive detector of monoenergetic phonons, and can be used to study phonon dynamics. The observed rate of optical dephasing is reduced relative to an equivalent occupation of 23-cm-1 phonons produced thermally. © 1985 The American Physical Society.