Inhomogeneous broadening of spectral lines in doped insulators

We briefly review work on the nature of inhomogeneous broadening of spectral lines in doped inorganic insulating crystals, and its effect on dynamical processes. Evidence from fluorescence line-narrowing and spectral holeburning suggests that inhomogeneities act as microscopic perturbations, shifting the energy of near-neighbor dopants by an amount comparable to the overall inhomogeneous broadening. Magnetic inhomogeneities due to different nuclear spin configurations are small (≈kHz-MHz) but very important because they vary on the timescale of a spectral holeburning experiment and lead to spectral diffusion. © 1990.