Electron Excitation and Deexcitation Coefficients for the 3P2, 3P1, 3P0, and 1P1 Levels of Argon

Electron excitation and deexcitation coefficients have been measured for the first excited levels of Ar (3P0, 3P1, 3P2, and 1P1) using line absorption techniques to obtain excited state population densities in an Ar glow discharge in the pressure range of 0.2 to 10.0 Torr. In addition, several excitation transfer coefficients for excited Ar atom – ground state Ar atom collisions have been derived from the population density measurements and the results are in agreement with previous measurements obtained using pulsed Ar afterglows. The measured electron excitation and deexcitation coefficients yield velocity averaged cross sections for the various collision induced transitions. There is order of magnitude agreement with deexcitation cross sections calculated using a modified Thompson cross section and a Maxwellian distribution for the electrons. The assumption of a Maxwellian distribution is inappropriate for the calculation of electron excitation coefficients since the average electron energy is much smaller than the threshold for excitation of the first excited levels in Ar.