Electronic Excitations in LiF: 10-70 eV

In the past three years, a number of different interpretatons of the optical properties of LiF have appeared in the physics literature. We present new evidence which shows that most of these interpretations are incorrect in the soft-x-ray region, and for the first time we present measurements of anisotropies in the excitations in the ultraviolet region as a function of momentum transfer in single-crystal samples.