PRODUCTION AND LOSS OF N2+ IONS IN NITROGEN AFTERGLOW

The time dependence of the number density of nitrogen ions was studied in the pressure range of about 0.1 to 1.7 Torr by means of mass spectrometric probing of decaying nitrogen plasmas. The analysis of the N2+ decay curves showed that N2+ ions are produced in the afterglow by collisions between metastable nitrogen molecules. Energy level and radiative lifetime considerations indicate that one of the metastable molecules is in the a′1∑u} state, while the other metastable molecule may be in the same state or in the A3∑u+ or3Δu state. The surface catalytic efficiency for de-excitation of the metastable molecules involved upon striking the molybdenum covered plasma container walls was estimated to be smaller than 2×10-3 at a pressure of 0.09 Torr. If both interacting metastable molecules are in the a′1bEu} state the measurements result in a value of 1.3×10-18 cm2 for the cross section for destruction of this state by collisions with ground state nitrogen molecules. © 1969 Springer-Verlag.