Experimental and theoretical (e, 2e) studies of argon (3p) ionization in asymmetric geometry

Abstract

Experimental and theoretical triple-differential cross sections (TDCS) are presented for ionization of the outer 3p shell of argon by 200 eV electrons scattered through an angle of 15° and for ejected electron energies of 2, 5, 10 and 20 eV. A distorted-wave Born approximation (DWBA) and a hybrid DWBA-R-matrix (DWBA-RM2) calculation both reproduce the shapes of the TDCS when the slow electron is ejected near the momentum-transfer direction. Near the opposite direction, the DWBA-RM2 model also achieves good agreement with experiment for the higher ejected electron energies, but discrepancies are observed for the lower energies. This three-way joint study emphasizes that it is essential to include a proper treatment of exchange in modelling low-energy ionization.

Experimental and theoretical (e,2e) studies of argon (3p) ionization in asymmetric geometry

“…Experimental and theoretical (e,2e) studies of argon (3p) ionization in asymmetric geometry It has recently come to our attention that the experimental data in the recoil region of the triple differential cross sections (TDCS) presented in figure 1 of Stevenson et al (2005) were plotted at the wrong angles. This has significant implications for comparisons made between experiment and distorted-wave Born approximation (DWBA) and hybrid first-order DWBA-R-matrix (DWBA-RM2) calculations in this region of the TDCS.…”

Angular distributions of secondary electrons in fast particle-atom scattering

“…Prominent changes of β (in) nd (q,ω) take place with the weakening of variations, while q increases. Figure 9 shows the angular anisotropy nondipole parameters of knocked-out electrons γ (in) nd (q,ω) and η (in) nd (q,ω) given by (17) at q = 0.1 and 1.1, compared to similar parameters in photoionization γ nd (ω) and η nd (ω), determined by (32) and (33) for 3d Kr and 4d Xe subshells in RPAE. The difference between parameters for photoionization and fast electron scattering is quite large.…”

“…As concrete objects, we choose outer np 2 and subvalent ns 2 subshells of Ar, Kr, and Xe. The nondipole parameter ζ (in) nd was calculated for 3d Kr and 4d Xe, using the expression that follows from (17):…”

“…[12,13], and references therein). 2 Let us compare our approach to that developed in connection to the studies of the so-called (e,2e) reaction [14][15][16][17]. In most cases, the electrons were not fast enough and the first Born approximation in describing the incoming electrons was not valid.…”

“…The aim of this direction of research was clearly formulated in Ref. [17]: "A specific set of kinematics is completely defined by the method with the results yielding valuable information on the collision dynamics or on the momentum distribution of the struck atomic electron." It required developing approaches that permitted one to take into account the interaction between two outgoing electrons.…”