Angular distribution in the photoelectron spectrum of the ground and first excited vibrational bands of the X 2Σg+ state in N2+ measured as a function of photon energy

Abstract

Angle‐resolved photoelectron spectra were taken of the first ionization state of N2 as a function of photon energy using a monochromatized beam of polarized photons from the Wisconsin Synchrotron Radiation Center. From these results the angular parameters for the first two vibrational states were determined over a range of photon energies from 17.7 to 31.0 eV. In energy ranges where resonance absorption, accompanied by autoionization, is expected to occur, β for the first excited vibrational level (v 1) was frequently characterized by near zero values. In energy regions free of discrete autoionizationv 1 was found to have a value of β considerably larger (∼0.4 to 0.8 units) than that for the ground vibrational level (v 0). This result is shown to be in accordance with recent calculations by Dehmer e t a l., based on the effect of vibrational motion on β in the vicinity of a shape resonance.