(e,2e)ionization-excitation ofH2

Looking at Molecular Orbitals in Three-Dimensional Form: From Dream to Reality

“…The result is fully as expected; the n = 2 SBA momentum profile reproduces satisfactorily the experiment, as can be seen from Figure 15b. Thus the explanation proposed by Takahashi et al 148 is to a considerable extent acceptable even at the present stage. The last fact that Takahashi and others have deduced is the most direct one, in which EMS experiments on the ionizationexcitation processes of H 2 have been carried out by Asano et al, 156 at three different incident electron energy values (E 0 = 1.2, 2.0, and 4.0 keV) with higher precision having been achieved.…”

“…Thus a deconvolution procedure with curve fitting is required to obtain momentum profiles for the 2s· g , 2p· u , and 2p³ u transitions separately, for which relatively better statistics of experimental data are desired. Figure 14 shows ¦º-angle integrated binding energy spectra of He reported by Watanabe et al 74 and of H 2 by Takahashi et al, 148 both of which have been measured at E 0 = 1.2 keV. Upright bars indicate vertical ionization energies, showing transitions of He (H 2 ) to the n = 1 (1s· g ) ion ground state and the n = 2 (2s· g , 2p· u , and 2p³ u ) ion excited states as well as the double ionization threshold.…”

“…The larger difference observed in the 2p· u channel than that in the 2s· g channel is consistent with the findings of the EMS study on H 2 . 148 Thus the 2p· u results may particularly offer one an opportunity to study geometry effects of molecular orientation in the TS mechanisms, because the extent of the intensity difference between the (e,2e+M) and PWIA result is a rough measure of contributions of the TS mechanisms. Interestingly, the 2p· u experiments appear to show more significant deviation from the PWIA in the direction of the molecular axis.…”

“…One is motivated by interest in most directly probing the correlated motion of electrons, in twoelectron systems, He 72,74 and H 2 . 148 Another is a comparative study of binding energy spectra by means of PES and EMS, 86 which aims to achieve a more generalized understanding of ionization processes.…”

“…On the other hand, for the 2s· g channel contributions from the TS mechanisms are very small compared to those of the PWIA mechanism and the symmetry of the momentum profile is maintained. In this way, Takahashi et al 148 have arrived at and proposed in 2003 the rational explanation for the H 2 results.…”