Knowledge Bank

The absorption spectrum of the (2, 0) vibrational band of the $A2\Pi u-X2\Sigma g+$ system of the nitrogen molecular ion generated by discharge in the pulsed supersonic jet expansion has been observed by near-infrared diode laser spectroscopy. Signal-to-noise ratio greater than 40 at an effective time constant of 0.1 sec was obtained using the discharge modulation technique followed by dual-gated integration synchronous with a pulsed nozzle. The rotational temperature of the $N2-$ ion was typically 50 K in the discharge plasma in the pulsed supersonic jet expansion.