Kinetic energy dependence of cross sections for state-to-state vibrational excitation in collisions of <i>S</i> aniline with He

Abstract

The kinetic energy dependence of the v=0→1 excitation cross sections have been measured for the two lowest-frequency modes of aniline, induced by collisions with He in crossed, pulsed molecular beams. Mode 11, an out-of-plane bend of the -NH2 group, shows a linear onset at threshold, while the -NH2 hydrogen-inversion mode has an excitation cross section which is a strongly decreasing function of collision energy in the 150–2000 cm−1 energy range. The total vibrationally inelastic cross section is large—at least 15% of the total rotational excitation cross section. Excitations of several in-plane modes were not observed.