State-to-state rate constants for collision induced energy transfer of electronically excited NH2 with NH3

Abstract

Collisional energy transfer of NH2 in its electronically excited state à 2A1 is investigated with time-resolved Fourier transform emission spectroscopy. NH2 is produced by photodissociation of NH3 and relaxed to low rotational levels before excitation into the electronically excited state. Originating from collisions with NH3, rate constants for total collisional removal and state-to-state rate constants for rotational energy transfer within v2=4, Ka=1 with collision induced changes of |ΔKc|⩽3 are determined. The latter rate constants are fitted with several scaling laws. Among these, those based on the energy corrected sudden approximation work best. An approximate potential curve for the anisotropic part of the interaction potential is derived and verified with cross sections obtained with straight line trajectories. The rotational energy transfer originates primarily from collisions with small impact parameters. The observed rate constants for total collisional removal are in accordance with the collision complex model.