DISCRETE STRUCTURE IN 40-60-A REGION OF PHOTOIONIZATION CONTINUA OF ARGON KRYPTON AND XENON

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 NI 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 LII and LIII edges and the Kr MIII edge; namely Ar LII limit = 250·6 ± 0·3 eV; Ar L III limit = 248·5 ± 0·3 eV; Kr MIII limit = 215·0 ± 0·4 eV. The Xe NI limit was found directly to be 211·3 ± 2 ev. Synchrotron radiation from the 330 MeV Glasgow Electron Synchrotron was used as a background continuum to record the spectra photographically.