Abstract
The excited levels argon (Ar*;1 s5, 1 s4, 1 s3 and 1 s2) are populated by means of a DC discharge in argon-nitrogen mixtures. The densities of Ar* (nj;j=5, 4, 3, 2) are measured by optical absorption techniques.The deactivation cross-sections (Qjo) of Ar* (1sj) by N2 are determined from the dependence of nj on nitrogen fraction and are 0.75±0.10, 2.2±1.1, 0.32± 0.06 and <3.3 Å2 for the 1 s5, 1 s4, 1 s3 and 1 s2 levels respectively.
The (0, 2) band of N2 second positive system is observed at the same time and it is clarified that Ar* excites the N2 (C3IIu), υ'=0 level which is characteristic of the nonequilibrium rotational populations such as the enhanced structure and alternating population.The ratios of the excitation rates of the N2 (C3IIu), υ'=0 level by electrons and Ar* are obtained from analysis of the nonequilibrium rotational populations for different nitrogen fractions, and explained by considering nj and Qjo.The cross-section of rotational relaxation (30±10 Å2) is also obtained from study of the dependence of alternating populations upon the pressure.
The collisional mechanisms between Ar* and N2 are discussed mainly on the basis of the one-step mechanism consisted of the ArN2* complex proposed by Setser and Stedman.
