(e, 2e) ionization measurements from the 3 sigma(g) and 2 sigma(*)(u) states of N2-comparison between experiment and theoretical predictions of the effects of exchange, polarization and interference

摘要

Gao et al (2005 Phys. Rev. A 72 032721) have predicted a Young's type interference effect in the fully differential cross sections for ionization of the 3 sigma(g) state of N-2 for highly asymmetric collisions with one electron detector fixed at very small scattering angles (1. or 10.). The purpose of this work was to look for this interference effect at a larger scattering angle. (e, 2e) ionization measurements have been conducted from the 3 sigma(g) and 2 sigma(u)* states of N-2 in a coplanar asymmetric geometry, where one electron emerges in the forward direction and the correlated electron is measured as a function of scattering angle. Both final-state electrons have an energy of 30 eV, and the forward scattering angle was theta(a) = 22 degrees relative to the incident beam direction. The theoretical prediction is that there should be a strong interference peak near 180 degrees. The measurements were carried out from the 3sg state over a range of scattering angles from theta(b) similar to 10 degrees to theta(b) similar to 170 degrees using a magnetic angle changing spectrometer. The present experimental results for 3sg find a normal binary peak plus another peak at back angles in the vicinity of 180 degrees. Consequently, this work supports the possibility of a strong Young's type interference effect for small fixed scattering angles.