Triply differential (e,2e) cross sections for ionization of the nitrogen molecule at large energy transfer

Abstract

Measurements of the (e,2e) triply differential cross sections (TDCS) are presented for the ionization of the nitrogen molecule in coplanar asymmetric geometry at an incident energy of about 600 eV and a large energy transfer to the target. The experimental results are compared with state-of-the-art available theoretical models for treating differential electron impact ionization of molecules. The experimental TDCS are characterized by a shift towards larger angles of the angular distribution with respect to the momentum transfer direction, and by a large intensity in the recoil region, especially for ionization of the 'inner' 2σ g molecular orbital. Such shifts and intensity enhancement are not predicted by the model calculations which rather yield a TDCS symmetrically distributed around the momentum transfer direction.

Experimental and theoretical investigation of the triple differential cross section for electron impact ionization of pyrimidine molecules

“…Interestingly, the HOMO binary peak here also appears quite narrow. This is in contrast to previous dynamical (e, 2e) studies on molecules, including for tetrahydrofuran, 17 formic acid, 16 water, 42 nitrogen, 43 and methane, 14 under similar kinematics in which very broad binary peaks have been observed for ionization of the HOMO.…”

Differential studies and projectile charge effects in ionization of molecular nitrogen by positron and electron impact

“…For example, in fully kinematic studies the binary electron emission (resulting from 2-body interactions involving just the incoming projectile and a single target electron with the other bound electrons and target nucleus acting as non participating spectators) was predicted to be enhanced (reduced) for positron (electron) impact; while just the opposite was predicted for the recoil intensity (corresponding to interactions where the ejected electron also interacts with the target nucleus as it leaves). The directions of the binary and recoil lobes were also predicted to have opposite shifts with respect to the momentum transfer direction [5][6][7][8][9]. Many theoretical studies performed since then arrive at similar predictions.…”

“…One particular interest in comparing positron and electron impact data are differences in the interaction kinematics associated solely with the opposite projectile charges. These differences provide stringent tests of theory because first-order perturbation theories predict identical total and differential cross sections for higher energy electron and positron impact whereas more sophisticated approximations developed in the 1980's and 90's predicted differences in the differential electron emission measured as a function of the momentum transfer [2][3][4][5][6][7][8][9][10][11][12][13]. For example, in fully kinematic studies the binary electron emission (resulting from 2-body interactions involving just the incoming projectile and a single target electron with the other bound electrons and target nucleus acting as non participating spectators) was predicted to be enhanced (reduced) for positron (electron) impact; while just the opposite was predicted for the recoil intensity (corresponding to interactions where the ejected electron also interacts with the target nucleus as it leaves).…”

The Distorted-Wave Born Approach for Calculating Electron-Impact Ionization of Molecules

“…We would like to emphasize that we are not trying to provide an overview of all the low to intermediate energy work that has been done-only the work performed in the last few years. Figure 1 shows a comparison of the Paris data [170] with our M3DW results and the First Born Approximation-Two Center Continuum (FBA-TCC) calculation of Joulakian and co-workers. The cross-sections presented in Figure 1 exhibit the typical (e,2e) pattern normally found for ionization of atoms-a large peak at small scattering angles and a small peak at large scattering angles (normally at about 180 • from the large peak).…”