Thermal energy He scattering was used to measure the isothermal desorption of NO from Pt(111) at 343 to 383K. By taking account of vibrational degrees of freedom in order to calculate the residence time of the molecules, the energy of adsorption was estimated to be -29.8kcal/mol, while the repulsive interaction between molecules was 6.1kcal/mol. The macroscopic diffusion of NO on Pt(111) was measured at between 313 and 358K. The technique involved the use of a He beam to monitor the time dependence of the coverage at a well-defined surface spot, as the adsorbed molecules diffused out of the spot. At low coverages, the NO diffusivity could be described by:

D(m2/s) = 0.0024 exp[-11.8(kcal/mol)/RT]

M.Croci, C.Félix, G.Vandoni, W.Harbich, R.Monot: Surface Science, 1994, 307-309, 460-4