High resolution spectrum of the N_2^+ Meinel system to 11 250 Å

Abstract

This spectrometric investigation of the emission of the A2Πui→X2Σg+ band system of the nitrogen molecular ion has yielded the wave numbers of 1267 individual lines in eight bands. Cooled photo-multipliers were used up to the 1-0 band at 9200 Å and a cooled intrinsic germanium photodiode was used for the 0-0 band. The spectra were obtained using a specialized hollow cathode source and a 5-m Jarrell-Ash spectrograph adapted to spectrometric operation through the installation of an exit slit translated with a lead screw assembly driven by a stepping motor. Improved molecular constants and vibrational term values have been determined as well as the origins of the 0-0 and 1-0 bands which have not previously been subject to direct measurement and which specify the bottom of the A2Πu potential curve. Observation of a very intense 0-0 band indicates a large population for the υ = 0 level of the A2Πu state under the conditions of the experiment. It is concluded that collisional transfer of excitation between electronic states is responsible for the accumulation of population in this lowest excited level of N2+.