Nonradiative transition dynamics in alexandrite

Abstract

The first direct picosecond time-resolved measurement of the nonradiative transition dynamics between the excited 4T2 pump band and the metastable 2E storage level of the trivalent chromium ion in alexandrite is reported. The nonradiative relaxation times of 17 ps for intra-4T2 vibrational transitions, and 27 ps for 4T2→2E electronic transition are obtained. The thermal repopulation rate of the 4T2 state from the metastable 2E level is of the order 3.5×109 s−1.