Energy-transfer reactions between He(2 3S) and Ne( 3P 0.2) metastable atoms and PN radicals

Abstract

Energy-transfer reactions between He(2 3S) and Ne( 3P 0.2) metastable atoms and PN radicals have been investigated by emission spectroscopy. Thirteen new PN + (B 1Σ + −X 2Σ +) emission bands were found in addition to eight previously identified bands in the range 305–395 nm. From these observed band-head wavelengths, the following molecular constants were obtained for the X and B states of PN + : PN + (X): ω c = 1306 ± 3 cm −1, ω c x c = 7.9 ± 0.7 cm −1, PN − (B): T c = 31354 ± 6 cm −1, ω c = 719 ± 3 cm −1, ω c x c = 1.6 ± 0.7 cm −1. The PN + (B) state vibrational population was estimated from the emission intensities and the calculated Morse Franck—Condon (FC) factors for the PN + (B–X) transition. Both the results obtained by He(2 3S) and Ne( 3P 0.2) Penning ionization shifted to lower vibrational levels in comparison with the calculated FC factors for vertical PN(X) → PN + (B) ionization. Besides PN + (B–X) emission, unidentified bands were observed in the 231–236 nm region in the helium afterglow, probably originating from PN or PN −.