Electron-impact study in valence and autoionization resonance regions of argon.

Abstract

The recently built electron-energy-loss spectrometer (EELS) (typical FWHM 60 meV) was employed to measure the EELS spectra of argon in the discrete and autoionization resonance regions at a 2.5-keV impact energy and a mean scattering angle of 0\ifmmode^\circ\else\textdegree\fi{}. Relative differential optical oscillator strength spectra were established by multiplying the EELS spectra by the known Bethe-Born conversion factor of the spectrometer, and were normalized at a single point in the smooth continuum using the absolute values reported by Chan et al. [Phys. Rev. A 46, 149 (1992)]. The absolute oscillator strengths corresponding to these energy regions are reported and compared with previously published experimental and theoretical values. The values of parameters q, ${\mathrm{\ensuremath{\rho}}}^{2}$, ${\mathit{E}}_{\mathit{r}}$, and \ensuremath{\Gamma} for autoionization resonances involving states 3s3${\mathit{p}}^{6}$np $^{1}$${\mathit{P}}_{1}^{0}$ (n=4, 5, and 6) have been determined.