Experimental inelastic differential cross sections for electronic excitation in atom–atom and atom–molecule collisions

Abstract

Measurements of inelastic differential scattering cross sections for the electronic excitation of alkali metal atoms in collisions with various atoms and molecules are reported.

A fast, pulsed alkali atom beam, produced by charge exchange, crosses a thermal energy target beam and is then detected by a surface ionization detector, which is fixed in position at a distance of about 75 cm from the scattering region. The angle of deflection can be changed by moving the alkali beam source around the target. The energy loss of the scattered particles is analysed by a time-of-flight measurement.

Measurements have been performed for potassium atoms scattered by rare gas atoms, and for the systems K—N₂, Na—N₂, K—CO and K—K. The energies range from 100 to 200 eV, the angles from 0 to several degrees (laboratory system). In the alkali-rare gas collisions, the inelastic scattering portion is very small and cross sections have not been determined so far. The same holds for Na—N₂. Large inelastic cross sections, however, are found in the case of K—N₂, K—CO, and K—K. A preliminary evaluation of the data is discussed.