Spin Anisotropy for Excitation in Collisions between Two One-Electron Atoms

Abstract

The singlet and triplet contributions of excitation cross sections are studied theoretically for collisions between various two one-electron atoms. The spin anisotropy is shown to have a general behavior in the important impact energy range. At low energies triplet cross sections dominate completely over the singlet ones while the opposite is true when the active electron and projectile velocities are comparable. Beyond the matching velocity regime singlet and triplet contributions become identical. We propose a general dynamical interpretation based on the analysis of the time dependency of the electron probability density and probability current density.

Cross sections in He+ + H collisions for the energy region 1–100 keV u−1

“…The cross sections for H(2p) excitation are shown in figure 3(a), which includes the experimental data of Mckee et al [13] and Geddes et al [14], and the theoretical cross sections of Errea et al [32], Ermolaev et al [24], Kuang et al [25], and Liu et al [26]. The data of Youg et al [12] The cross sections for H(2s) excitation are compared in figure 3(b), which shows the theoretical cross sections in AOCC1e calculations of Kuang et al [25] and Liu et al [26], and those in AOCC2e of present calculation and Wang et al [35]. These theoretical cross sections are similar in behavior below 20 keV u −1 .…”

“…The semiclassical atomic orbital close-coupling calculations within two-electron treatment (AOCC2e) were reported by Jackson et al [34], Ermolaev et al [24], and Wang et al [35]. The continuum channels are not considered in references [24,34].…”

“…The continuum channels are not considered in references [24,34]. The cross section for H(2s) excitation was presented in [35], where the details were not written for the calculation. In the present work, we have applied the AOCC2e calculation including continuum channels to calculate the cross sections for the elastic, H(n = 2) excitation, electron capture, and ionization processes.…”

Proton-beam stopping in hydrogen

“…The spin effects are expected to be small in the energy range between 10 keV and 3 MeV where we apply our method. However, at low energies, in particular around 10 keV and below, the spin effects become important [13][14][15][16]. Nevertheless, to our best knowledge, there has been no attempt to include them in stopping power calculations.…”

Theoretical Investigation on Excitation, Ionization and Capture in H(1 s , 2 s ) + H(1 s , 2 s ) Collisions

“…[15] Coupled-channel calculations have been reported to have better results for the cross sections of H(2s), H(2p), H + and H − in H(1s)+H(1s, 2s) collisions. [16−18] The results of hidden crossings method [1,19] have obtained an excellent agreement with experimental data of H + in H(1s)+H(1s) collisions in the energy range of 0.05-1 keV. One-electron description [2] and twoelectron self-consistent-field description [20] of closecoupling approach have been carried out for H(2s), H(2p) and H + cross sections in H(1s)+H(1s) collisions, having the best agreement with the experimental data till now, still with discrepancies for H(2p) cross section unresolved.…”