Vibrational excitation in H2 and D2 electric discharges

Spontaneous Raman scattering has been used to measure the effective vibrational temperature of the v=1 level as a function of input power in a self-sustaining low pressure dc glow discharge in pure H2 and D2 gases. A nonmonotonic dependence of vibrational temperature on input specific power, yielding Tv=1440–1960 °K in H2, has been measured downstream of the discharge. Results of numerical calculations modeling the discharge/afterglow are presented. The agreement between theory and experiment is good and suggest that the behavior observed is caused by the effect of the temperature dependent vibrational–translation energy transfer rate.