Excitation of 2 1S, 2 1P and 3 1P, 3 3P levels of helium in He+ on He collisions at a few hundreds eV

Photon ? ion angular correlations for He+ + He and He+ + Ne collisions

“…The authors concluded that the//contribution was predominant for all their measurements and they gave an interpretation, in which f~ = 0 was assumed. Figure 10 shows the potential curve system, which Rahmat et al [5] used for the interpretation of the He++He n=2 excitations. It is based on quantum chemical calculations by Stern et al [-23, 24] and it provides a good explanation for the experimental facts known so far.…”

“…In the energy region of interest here, both cross sections are increasing with energy, possibly with a faint oscillatory structure. The differential cross section for the 1p channel at 100 eV collision energy was measured by Rahmat et al [5]. It shows the typical behavior for an inelastic process.…”

“…The n=2 excitations in He++He collisions have been the subject of a significant number of experimental [5,[17][18][19][20][21] and theoretical [22][23][24][25] investigations. Integral cross sections as a function of energy for the channels He § (ls2p) 1p, 3p were measured by Dworetsky and Nowick [18].…”

“…Experiments of this type have become a standard experiment for inelastic electron-atom collisions [6]. For atom-atom collisions, only few experiments have been reported so far [2][3][4][5]. We present results of photon-ion coincidence experiments for the processes He + +He(ls2)lS ~ He + +He(ls2p)lp…”

“…Their influence upon the photon distributions is unimportant, however, due to the slow angular variation. For the evaluation of the He results, (1) was reduced by setting All =-AI_ 1, according to (5). Because the measured parameters are in unknown units, we form the ratios…”