X-Ray Spectroscopic Investigation of Ammonium Chloride

Abstract

The K α emission and K β emission spectra in fluorescence of Cl - in NH 4 Cl are measured with a two-crystal vacuum spectrometer. The Cl - K β emission spectrum is presented along with the Cl - K absorption, Cl - L 2,3 absorption and vacuum ultraviolet (VUV) absorption spectra of NH 4 Cl, reported previously. By using the measured emission spectra and the VUV absorption spectrum, the energy position of the bottom of the conduction band is shown in the Cl - K absorption and Cl - L 2,3 absorption spectra. The first sharp peak of the Cl - L 2,3 absorption is identified as being due to a core exciton, the energy level of which is formed below the bottom of the conduction band. The binding energy of the exciton is estimated to be 1.1( ±0.1) eV. The second sharp peak is related to two types of excitons; a stable exciton and a metastable exciton.