Absolute optical oscillator strengths for the electronic excitation of atoms at high resolution. III. The photoabsorption of argon, krypton, and xenon

Absolute oscillator strengths for the photoabsorption of argon, krypton, and xenon in both the discrete and continuum regions have been measured. The results are compared where possible with previously published experimental and theoretical data. The present work is a continuation of recently reported measurements for helium [Chan et al., Phys. Rev. A 44, 186 (1991)] and neon [Chan et al., Phys. Rev. A 45, 1420 (1992)] obtained using the dipole (e,e) method at both low and high resolution. Using the low-resolution dipole (e,e) spectrometer [with a full width at half maximum (FWHM) of about 1 eV], absolute photoabsorption oscillator strength spectra for the valence and inner shells of argon, krypton, and xenon were obtained up to equivalent photon energies of 500, 380, and 398 eV, respectively. The high-resolution dipole (e,e) spectrometer (FWHM of 0.048 eV) was employed to obtain absolute photoabsorption oscillator strengths for the discrete electronic transitions from the ground states to the ${\mathit{ms}}^2$ ${\mathit{mp}}^5$ns and ${\mathit{ms}}^2$ ${\mathit{mp}}^5$nd ${(}^2$ ${\mathit{P}}_{3/2,1/2}$) manifolds where m=3, 4, and 5 for argon, krypton, and xenon, respectively. The absolute optical oscillator strength scales were obtained by single-point continuum normalization of the Bethe-Born converted electron-energy-loss spectra using the recently reported absolute optical data of Samson and Yin [J. Opt. Soc. Am. B 6, 2326 (1989)] for argon, krypton, and xenon atoms. High-resolution absolute photoabsorption oscillator strengths were also obtained in the energy regions of the autoionizing resonances corresponding to excitation of the inner-valence s electrons of argon, krypton, and xenon.