Rotational- and Spin-State Distributions: NO Thermally Desorbed from Ru(001)

Abstract

Rotational-state distributions have been measured for the first time in molecules thermally desorbed from a metal single crystal. Laser-excited fluorescence has been used to monitor, under ultrahigh-vacuum conditions, the desorption of NO from Ru(001). The population distribution for those states with less than 400 ${\mathrm{cm}}^{-1\mathrm{}}$ of rotational energy (including spin) can be represented by a single Boltzmann factor, $T_{\mathrm{rot}}=235\mathrm{}\pm 35$ K, significantly lower than the surface temperature at the desorption maximum, $T_S=455\mathrm{}\pm 20$ K.