The rovibrational distribution of H 2 and HD formed on a graphite surfaceat 15-50 K

The rotational distributions of H 2 and HD formed on a highly oriented pyrolitic graphite surface at temperatures of 15-50 K have been measured using laser spectroscopy. The population of the rovibrational levels ν = 1 , J = 0 - 4 and ν = 2 , J = 0 - 4 has been observed and the average rotational temperatures of the nascent H 2 and HD molecules have been determined. We find that the average rotational temperature of the newly formed molecules is much higher than the surface temperature on which they have formed. We compare our results with other recent experimental data and theoretical calculations.