Molecular compton profiles from inelastic atom-electron scattering

Abstract

Recent measurements of the electron loss peak from H~-ions impinging on Ar have been analyzed in terms of projectile Compton profiles (CP). It is shown that projected momentum distributions, i.e. CP's, can be determined for the molecular ion H~-.Recently it has been demonstrated that Compton profiles (CP), i.e. projected electron momentum distributions, of either target atoms or projectile ions can be obtained by inelastic ion-electron scattering [1]. It is the aim of this paper to show that existing data of electron loss measurements are sensitive enough to extract the Compton profile of H~-molecules. (For a recent review of molecular Compton profiles see [2].) We have analyzed the electron loss peak (ELP) measurements of K6v6r et al. [3] for H~--Ar and He +-Ar collisions in terms of CP's. If the collision velocity v is much larger than the initial orbital velocity v~ of the scattered electrons, the double differential cross section (DDCS) for the emission of projectile electrons can be factorized [1] :Here, (da/df2)e is the elastic cross section for scattering an electron with velocity v at a screened target nucleus and Jp(p=) the CP of the projectile:O~(p) is the initial electron wave-function, E e the electron lab energy and Eem the electron energy at which the electron loss peak occurs (atomic units are used). The essential feature of (1) is that the DDCS factorizes into a cross section which contains all the information of the electron-atom interaction and which is essentially constant in the region of the ELP and a CP which is characteristic of the electron's initial state. For the evaluation of (1) where N is a normalization constant. Putting (4) into (2) yields a directional CP which has to be averaged over all angles between the momentum component p~ (which is parallel to the beam direction) and the bond direction /~ assuming an isotropic distribution of/~ with respect to $ [7]. Figure 1 shows the comparison of experimental data of [3] for 0.8 MeV/amu He + (circles), 0.8 MeV/ amu H~-(closed triangles) and 1.995 MeV/

A test of wavefunctions for H+2(2Σ+g) via the study of Compton profiles

“…The (J(q))vlb for H: and D: , calculated using two sets of distribution factors (the FC and VBD), are given in table 1. Bell (1984) analysed the ELP (at an emission angle of 135"), reported by Kover et a1 (1983), in terms of CP at the incident energies of 0.8 and 1.995 MeV amu-' from Hl-Ar collisions. The obtained CP were shown (Bell 1984) to be independent of incident energies and targets.…”

“…Bell (1984) analysed the ELP (at an emission angle of 135"), reported by Kover et a1 (1983), in terms of CP at the incident energies of 0.8 and 1.995 MeV amu-' from Hl-Ar collisions. The obtained CP were shown (Bell 1984) to be independent of incident energies and targets. This demonstrated that the PWLA is valid for this collision process at those incident energies.…”

“…The ion-atom scattering technique has been demonstrated to measure CP for a number of atomic and molecular targets (Burch et .a1 1973, Jakubassa 1980and references therein, Bockel and Bell 1983. Recently Bell (1984) calculated the CP of Het and H i to compare with the CP measured from the ion-Ar collisions reported by Kover et al (1983). He showed that theory and experiment are in good agreement for He+ and H:.…”