Rotational and vibrational distributions of N2(C 3Πu) excited by state-selected Ar(3P2) and Ar(3P0) metastable atoms

Abstract

Abstract The vibrational distributions of N 2 (C 3 Π u ) and the rotational distributions of N 2 (C 3 Π u , ???′ = 0) excited by energy transfer from state-selected argon metastable 3 P 2 or 3 P 0 atoms to nitrogen molecules were studied in the afterglow of a pulsed electrodeless discharge at 300 and 90 K. Selective depopulation of one metastable argon species was achieved by optical pumping using a tunable cw dye laser. The density of the metastable argon atoms and the intensity of the rotational lines or vibrational bands of the N 2 (C 3 Π u → B 3 Π g ) fluorescence were monitored in the afterglow. Results obtained at 90 K clearly establish a two-component rotational distribution. Rate coefficients for the excitation of the individual vibrational levels of N 2 (C 3 Π u ) by each argon metastable species were determined. The golden-rule model is unable to explain the vibrational distributions obtained by energy transfer; the vibrational population distribution of N 2 (C 3 Π u ) excited by Ar( 3 P 0 ) clearly shows this point.