Energy dependence of the differential photoelectron cross sections of molecular nitrogen

Abstract

The angular distribution of photoelectron intensity for molecular nitrogen was studied using He I and Ne 1 resonance line discharge light sources. Studies of photoelectron angular distributions covering a range of photon energies, and thus a range of photoelectron energies, are possible using the weaker high order lines in each discharge as well as the principal lines. Peaks in three photoelectron bands of N 2 were studied at the photon energies 16.85, 19.78, 21.22, 23.09, and 23.74 eV, where possible. We find that the v' = 0 peak of the X 2 I.i band has abnormally high intensity and, at the higher photon energies, an abnormally low angular distribution asymmetry parameter, /3. Several mechanisms for this anomaly are discussed, including autoionization, the variation of electric dipole transition moments with internuclear distance, and possible shape resonance phenomena. None of these explanations is completely in agreement with all theoretical and experimental evidence.

A capillary discharge tube for the production of intense VUV resonance radiation

“…Particularly for the A 'nu band the present values agree excellently with those of Mintz and Kuppermann (1978) and Kreile and Schweig (1980). The variation in the angular distribution for different U' of this band was first observed by Carlson (197 1).…”

“…whereas the variation of p across the vibrational progression A 2 n , (z. "=O, 1, 2, 3) can be explained by variation of p with photoelectron kinetic energy (Mintz and Kuppermann 1978). Angular distribution studies for the above reactions have also been carried out using monochromated synchrotron radiation (Marr et a1 1979, Holmes andMarr 1980).…”

Photoelectron spectroscopy of ethylene, isobutylene, trimethylethylene, and tetramethylethylene at variable angle

“…29 However, photoelectrons corresponding to formation of these different peaks have different kinetic energy and can therefore have slightly different values of f3 due to the variation of this parameter with electron kinetic energy. 13 We have studied such variations with the present apparatus over the A 2 n. state in N2 30 and the A 2 II state in C0. 31 The variation of {3 across a given electronic band can be used to infer the variation of f3 for a fixed vibrational transition with electron kinetic energy (i.e., with photon energy) if autoionization does not occur.…”