Discrete structure in the 40-60 Angstrom region of the photoionization continua of argon, krypton and xenon

Abstract

The 40-80 Angstrom region of the photoionization continua of argon, krypton and xenon has been studied, revealing discrete resonances in argon and krypton and a very weak N_I edge in xenon. The resonances, due to inner-shell p electron excitation to autoionizing levels of Ar I and Kr I, occur around 50 Angstrom in argon and 58 Angstrom in krypton, yielding new values for both the Ar L_II and L_III edges and the Kr M_III edge; namely Ar L_II limit = 2506 ± 03 eV; Ar L_III limit = 2485 ± 03 eV; Kr M_III limit = 2150 ± 04 eV. The Xe N_I limit was found directly to be 2113 ± 2 ev. Synchrotron radiation from the 330 MeV Glasgow Electron Synchrotron was used as a background continuum to record the spectra photographically.