Multiphoton ionization detection of NO scattered from solid surfaces

This paper describes experiments where resonantly enhanced multiphoton ionization was used to determine rotational state distributions of NO scattered from a copper surface in a high vacuum. A pulsed valve produced a high intensity beam of NO seeded in He with a well-defined translational energy and a rotational temperature of 7 K. With a 0.28 eV incident beam and a surface temperature of 77 K the scattered beam was found to have a rotational temperature of 230 K. When the surface temperature was raised to 300 K, the scattered beam temperature approximated that of the surface. For the surface at either temperature, significant population of the X 2Π3/2 state was found. The variation of the scattered beam temperature with surface temperature is in qualitative agreement with calculations based on the hard cube model.