A study of the turn-up effect in the electron momentum spectroscopy

Abstract

Recently, a number of electron momentum spectroscopy measurements for the ionization of atoms and molecules have shown that the triple differential cross section (TDCS) has an unexpected higher intensity in a low momentum regime (Brunger M J, Braidwood S W, Mc Carthy I E and Weigold E 1994 J. Phys. B: At. Mol. Opt. Phys. 27 L597, Hollebone B P, Neville J J, Zheng Y, Brion C E, Wang Y and Davidson E R 1995 Chem. Phys. 196 13, Brion C E, Zheng Y, Rolke J, Neville J J, McCarthy I E and Wang J 1998 J. Phys. B: At. Mol. Opt. Phys. 31 L223, Ren X G, Ning C G, Deng J K, Zhang S F, Su G L, Huang F and Li G Q 2005 Phys. Rev. Lett. 94 163201, Deng J K, et al 2001 J. Chem. Phys. 114 882, Ning C G, Ren X G, Deng J K, Su G L, Zhang S F and Li G Q 2006 Phys. Rev. A 73 022704). This surprising result is now called the turn-up effect. Our aim is to investigate such an effect by studying the case of the ionization of atomic hydrogen in an excited state using the 3C model (Brauner M, Briggs J S and Klar H 1989 J. Phys. B: At. Mol. Opt. Phys. 22 2265) which is able to describe all the measured results of the single ionization of atomic hydrogen in its ground state for an incident energy beyond 200 eV. A comparison is also made of the findings of the present method with those of the plane wave impulse approximation and distorted wave models.

Dynamic effects in electron momentum spectroscopy of sulfur hexafluoride

“…For these cases, experiment found a higher intensity than was predicted by the PWIA in the low momentum region, as well as an impact-energy dependent effect. For atomic orbitals, the observed higher intensity at low momenta can be well reproduced by distorted-wave calculations [5,6,10]. For molecules, calculations considering molecular vibration indicate that the higher intensity at the low momenta can be partly, but not totally, attributed to vibrational effects, see e.g.…”

Application of a post-collisional-interaction distorted-wave model for (e, 2e) of some atomic targets and methane

“…The BBK final state is described by three Coulomb waves taking into account the interaction between the outgoing electrons with the nucleus as well as the electron-electron repulsion, while the incoming electron is described by a plane wave. The disadvantage of the model is that the distortion effects are not included, limiting its application for light targets like hydrogen, where the results are impressive [18,19]. Furthermore, it has been found that the BBK model is not able to reproduce the recoil peak for even small molecular targets [20,21].…”

The second Born approximation for the double ionization of N2by electron impact

“…From the theoretical point of view, the problem of the ionization of atomic hydrogen by electrons is solved by nonperturbative theories such as exterior complex scaling [17], convergent close coupling (CCC) [18], R matrix theory [19,20] and time-dependent close coupling [21]. The Brauner-Briggs-Klar (BBK) model [22] (which is a perturbative theory) yields good agreement with experiments when the incident energy is greater than 150 eV [23]. Finally it is necessary to apply perturbative theories (such as the wellknown Born approximation) when one studies the single ionization of heavier atoms and molecules.…”