Thermomodulation Study of Plasmons and Longitudinal Excitons in Alkali Halides

Abstract
Thermoreflectance measurements on LiF and KCl were made from 10 to 30 eV using synchrotron radiation. Analysis of the differential dielectric and electron-energy-loss functions shows that the energy-loss peak generally attributed to the valence plasmon actually arises from the plasmon and overlapping longitudinal-exciton-like peak(s).