Abstract

Persistent spectral holes may be burned into the IR vibrational spectrum of ${\text{NO}}_2^{-}$ ions matrix isolated in alkali-halide lattices. The holes are formed when ions, which are resonantly excited by a tunable diode laser, occasionally reorient in the lattice. The frequency shift and inhomogeneous broadening of the vibrational mode both result from lattice strains. A hole burned in a spectral feature arising from low-frequency librational levels in combination with the bending mode of ${\text{NO}}_2^{-}$ impurities in KCl at low temperatures (~800 cm⁻¹) not only produces a hole at the laser frequency but also produces a hole in every other transition. The nonresonant spectral hole positions and shapes are highly correlated to the resonant hole position and shape. The hole burning results indicate that the inhomogeneous broadening in these bands is caused by a distribution of symmetrically split librational levels.

© 1987 Optical Society of America