THE ROLE OF NUCLEAR-SPIN IN INELASTIC NA(3P)+H-2 COLLISIONS

Using the CARS (coherent anti-Stokes Raman spectroscopy) detection technique, we measured the rotational distribution in the nu = 3 vibrational level of the para-H2 modification of the hydrogen molecule after inelastic collision with the Na(3p) atom. Para-H2 was used in a flowing-regime cell at a temperature of 523 K and at pressures of para-H2 ranging from 10 to 200 mbar. Our measurements show that the para-H2 modification is conserved in inelastic collisions. The conservation of the nuclear spin was also studied at very low hydrogen pressures, where we obtained the non-thermal rotational distribution at the highest attainable vibrational level nu = 3.