Absorption Spectra of Alkali Fluorides in the Extreme Ultraviolet Region

Abstract

Absorption spectra of five kinds of alkali fluorides, namely LiF, NaF, KF, RbF and CsF are investigated at room temperature in the wavelength region from 500 A to 1000 A. In LiF and NaF only broad bands are observed except for the first exciton bands. In KF a doublet with a deep depression between the components is observed around 21 eV. In RbF and CsF quartets are observed around 17 eV and 14 eV, respectively. These multiplets are assigned to the exciton absorptions related with the transition from the uppermost cation core levels to the conduction bands.