The Oblique Incidence Transmission Spectra of KCl and KBr for the Polarized Extreme Ultraviolet Radiation

Abstract

Oblique incidence transmittances of alkali halide thin films (KCI and KBr) for polarized radiation were investigated in the fundamental absorption region of the extreme ultraviolet. The direct measurements of the transmittance ratio (T_p⁄T_s) spectra were performed, and the plasma resonance absorption was evidently demonstrated as a prominent peak in the (1−T_p⁄T_s) spectra of KCl and KBr at 14.1 and 13.0 eV, respectively. The peaks well correspond to the previously reported peaks in the electron energy loss spectra and also in the loss function spectra calculated from the optical constants. The plasmon peaks were able to be distinguished from other subsidiary structures due to the longitudinal excitons associated with the transverse excitons.