Abstract

We have used UV laser excitation at 308 nm to excite nonresonantly the vibrational stretch mode of the CN⁻ ion doped in alkali-halide crystals. The energy transfer stems from the creation of color centers near the molecular defect. IR fluorescence from the deexcitation of the CN⁻ vibrational manifold in the ground electronic state is observed to yield a series of anharmonically shifted (~25-cm⁻¹) transitions near 2000 cm⁻¹. The strength of the IR emission grows with increasing host lattice constant and a shift in population to higher vibrational states v with decreasing sample temperature is observed. For Rbl + 0.5% KCN, this shift results in population inversion between the v = 2 and v = 1 levels at liquid He temperature. Inversion is quickly obtained (<1 μs) after the 40-ns UV laser pulse. At longer times a redistribution of the vibrational population is driven by V-V transfer between the molecular defects. (12 min)

© 1987 Optical Society of America