Free-collision model calculations for the electron detachment of anions by noble gases

Abstract

An extended version of the free-collision model was employed for the calculation of the electron detachment cross sections of several anions, with npi structures, i = 2, 3, 5 and 6, namely B−, Al−, C−, O−, S−, F− and Cl−, in collisions with noble gases in the intermediate-velocity regime. The calculations were performed only for the total electron detachment cross sections, except for the C− case, where partial electron-loss cross sections were obtained. Multiple electron loss was analysed within the independent particle model. The comparison of the calculated cross sections with the available experimental data shows good agreement in almost all cases.

Absolute cross sections for electron loss, electron capture, and multiple ionization in collisions ofC3+with noble gases

“…Most of these, as pointed out previously, refer to the He target, except for the sets of data from DuBois and co-workers [52,[59][60][61][62][63], the data from Saito et al [66], and our own published data [10,13]. We have also compared our results of the single-loss−multipleionization channel to calculations in the plane-wave Born approximation (PWBA) [70] and the extended free-collision model [40], together with an analysis of the antiscreening contribution to the single-electron loss made following the reasoning presented by Montenegro et al [71].…”

“…In that article, the authors presented a comparison of their experimental results with calculations of the total single-electron-loss cross sections as the sum of the two aforementioned mechanisms which contribute to the single-electron loss. In that work, the screening was calculated using the extended classical-impulse free-collision model as presented by Sigaud [40] and the PWBA, while the antiscreening was obtained from the PWBA extended sum-rule method of Montenegro and Meyerhof [70]. It was observed that the calculations using the free-collision model describe the experimental cross sections much better than the PWBA for both projectiles.…”

“…The solid lines are the sum of the screening contribution calculated using the extended free-collision model from Ref. [40] and the antiscreening contribution from Montenegro and Meyerhof [70], the dashed lines are the screening contribution from the extended freecollision model of Sigaud [40], the dotted lines are the sum of the screening and antiscreening contributions calculated within the PWBA [70], and the dash-dotted lines are the antiscreening contribution from Ref. [70].…”

“…Alternatives range from classical models, such as classical trajectory Monte Carlo methods [36][37][38] or the free-collision model (also called classical impulse approximation) [8,39,40], to more rigorous quantum mechanical calculations, the latter almost always restricted to collisions in which electron capture can be neglected [41][42][43]. Full quantum calculations which take into account the ionization of both collision partners, as well as charge transfer between them, are rare and have only very recently been done [9,10,[44][45][46].…”

“…In Sec. III, the experimental results for multiple ionization of He, Ar, Kr, and Xe targets by C 3+ for the single-capture−multipleionization, the single-loss−multiple-ionization, and the pure multiple-ionization channels are presented separately and compared with the existent experimental data and with calculations in the PWBA [70] and the extended free-collision model [40] for the single-loss−multiple-ionization process. Conclusions are drawn in Sec.…”