Direct Inelastic Scattering of N sub 2 From Ag(111) IV: Scattering from a High Temperature Surface.

We have measured the rotational state distribution and the angular momentum alignment and orientation of N sub 2 scattered from Ag(111) at 540 K. Using resonance enhanced multiphoton ionization, REMPI, we are able to probe the scattered flux as a function of the exit angle, theta sub (exit). For a modestly glancing incident beam (theta sub i = 30degrees) and incident translational energy, E sub i = 0.3 eV, the angular momentum alignment (tumbling vs. helicoptering) at both quasi-specular detection (theta sub (exit) = 35degrees) and superspecular detection (theta sub (exit) = 50degrees) is only weakly dependent upon the surface temperature. However, the angular momentum orientation (clockwise vs. counterclockwise rotation) is strongly affected by the surface temperature. Raising the surface temperature from T sub s = 90 K to T sub s = 540 K causes the orientation to decrease substantially. Stochastic trajectory calculations were carried out in conjunction with the experiments.