Velocity dependence of sensitized fluorescence in collisions of metastable argon and helium atoms with nitrogen

The interactions of metastable argon and helium atoms with nitrogen have been studied by observation of the fluorescence of electronically excited N2 and N2+. An effusive, velocity filtered, metastable atom beam intersects a supersonic nozzle beam of nitrogen seeded with helium to extend the relative energy range. The nozzle beam is modulated and the photon signal is extracted from background using a dual-channel photon counter. Relative cross sections for the production of N2(C 3Πu) in metastable argon–nitrogen collisions are reported over the energy range 0.06 to 0.36 eV. Cross sections for the production of N2+(B 2Σu+) in metastable helium–nitrogen collisions are reported over the energy range 0.03 to 0.16 eV.