Electronic excitation of K atoms in collisions with diatomic molecules: Thresholds and energy dependence from 1-5 eV

A velocity selected atomic potassium beam produced by sputtering has been utilized to study collisional excitation of K atoms by diatomic molecules. K*(4(2)P) was detected by its radiative decay. For N(2), NO and 02 the excitation thresholds coincide with the endoergicity of the 4(2)S -> 4(2)P transition, 1.6 eV (c.m.s.) whereas for CO the threshold occurs at 2.1 eV. The cross sections rise about Linearly with velocity above threshold and are of the order of 2 angstrom(2) at 4 eV.