NONRADIATIVE TRANSITION DYNAMICS IN EMERALD.

Summary form only given. A direct time-resolved measurement of nonradiative transition rates and decay times among the **4T//2 pump band, and the **2E metastable storage level of Cr**3** plus ions in emerald was performed using the picosecond excite-and-probe absorption technique. The experimental arrangement uses a frequency-doubled 5-ps 527-nm pulse derived from a Nd:glass laser to excite the higher-lying vibrational levels of the **4T//2 band. These excited vibrational levels relax predominantly via nonradiative transitions resulting in a growth of population in the zero and lower-lying vibrational levels of the **4T//2 state, and in the metastable **2E level. This growth of population is monitored by an infrared picosecond probe pulse which may be wavelength tuned from 2 to 5 mu m. The kinetics of excited-state transitions is studied by measuring the change in the optical absorption of the probe pulse as a function of the pump-probe delay time.