Excitation of the (5,2) band of the first positive band system of N2 by proton impact on nitrogen

Abstract

Excitation of the (5,2) band of the first positive band system of N2 by proton impact on nitrogen was observed in a beam experiment. The intensity of the (5,2) band varied linearly with target gas pressure, and, therefore, the excitation of this band can be attributed to the impact of primary particles on nitrogen molecules. Excitation cross sections were measured for proton energies ranging from 3.35–20.1 keV. The excitation cross section attains its maximum value of 1.2×10−18 cm2 at approximately 5.0 keV and decreases smoothly towards higher proton energies. The measured cross sections seem to fit a Bethe plot. The quadratic pressure dependence of the intensity of the first positive band system, observed during earlier measurements, may have been due to a large contribution of neutral hydrogen atoms to the excitation of the first positive band system, which has masked out the excitation by protons.