Hydrogen dissociation in a H-2-N-2 pulsed dc glow discharge

The absolute concentration of hydrogen atoms is measured in the positve col umn of a pulsed de discharge by two-photon absorption laser-induced fluores cence in H-2 and H-2-N-2 gas mixtures at constant pressure and current. The discharge pulse duration is varied from 10 mu sec to 1 msec. For shorter p ulse durations of 10 and 100 mu sec, the H-atom signal decreased monotonica lly with Hz concentration; for longer pulse durations of greater than or eq ual to 500 mu sec, the fractional dissociation of the H-2 is enhanced with increasing N-2 concentration. The change in H-atom production from direct e lectron impact dissociation of H-2 at short times compared to that from mul tiquantum vibrational energy transfer induced dissociation of H-2 at long t imes is determined from temporally resolved H-atom concentration measuremen ts.