Large-angle scattering of energetic electrons from Xe: A combined theoretical and experimental approach

Abstract

We study the inelastic excitations of Xe for electrons with relatively high energies (500 or 750 eV) scattered over large angles, both experimentally and theoretically. In particular, we focus on the shape and intensity of the spectra of inelastically scattered electrons at the sharp dip in the elastic cross section near 135 • at 750 eV. Under these conditions, the first Born approximation predicts virtually zero intensity. However, in reality, measurable intensity is observed. Calculations carried out using the relativistic distorted-wave method describe the measurements reasonably well. A comparison is made between the calculations and previously published high-resolution studies. Overall agreement is quite good, especially for the lowest-energy excitations, but substantial differences are found for certain higher levels. The theory reproduces quite well the variations in intensity of the inelastic excitations for measurements near the dip in the elastic-scattering cross section, somewhat surprisingly, as the theories for elastic scattering and inelastic scattering are developed along completely different lines.

Collisional-radiative model of xenon plasma with calculated electron-impact fine-structure excitation cross-sections

“…On comparison of the present oscillator strengths with the experimental as well as theoretical values from NIST, we find good agreement, except for the single 1s 0 →3d 1 transition. Oscillator strengths obtained from the present calculation for this transition are higher than the values reported in the NIST database [41], but match the theoretical values reported by McEachran et al [47]. The experiential values of Chan et al [44] and theoretical results of Zatsarinny and Bartschat [45] are lower and close to the NIST value.…”

“…The present results obtained using GRASP2K code gave the oscillator strengths in both the Babushkin and Coulomb gauge, which can be said to be equivalent to the length and velocity forms, respectively. We have also compared in this table the other available theoretical calculations reported in both the gauges [45][46][47][48].…”

“…It is important to note that since we are considering the j-j coupling scheme for our present calculation, the values of the oscillator strength represented in the Babushkin gauge can be considered more accurate than those in the Coulomb gauge. For the oscillator strengths of the dipole allowed transitions from the ground state to 1s i , 3d i and 2s i fine-structure levels, various experimental [17,[41][42][43][44] and theoretical results [45][46][47] are available in the literature. Molino et al [42] obtained them from absorption measurements, Suzuki et al [17,43] used electron energy loss spectroscopy for measurements and Chan et al [44] carried out the measurements using a photo-absorption technique.…”

“…Molino et al [42] obtained them from absorption measurements, Suzuki et al [17,43] used electron energy loss spectroscopy for measurements and Chan et al [44] carried out the measurements using a photo-absorption technique. On the theoretical side, all the available studies [45][46][47] used MCDF wave functions for the calculation of oscillator strengths. On comparison of the present oscillator strengths with the experimental as well as theoretical values from NIST, we find good agreement, except for the single 1s 0 →3d 1 transition.…”