A study of the A 2Πu electronic state of N2+ by velocity modulation laser spectroscopy

The velocity modulation laser absorption technique was employed to obtain the spectrum of the (15, 8) band of the A2Πu–X 2Σg+ system of N2+ and a rotational analysis was performed. Rotational constants for the upper vibrational level were derived. The determined molecular constants of the (15, 8) band combined with values determined earlier from other directly observed bands at lower v′ numbers were used in a vibrational analysis of the A–X band system. The vibrational temperature of N2+ in the plasma discharge was determined.