Dynamics of Nitrogen Scattering from Solid Surfaces: Experiment and Trajectory Simulations.

State-selective detection and time-resolved molecular beams techniques were used to investigate the dynamics of N_2 scattering from solid surfaces. A trapping-desorption channel as well as a direct inelastic channel were observed on all surfaces investigated. Rotational state and velocity distributions were measured as a function of incident energy and surface temperature for both channels. The rotational state distributions of the direct inelastic channel were found to depend linearly on both surface temperature and incident energy. The absence of rotational rainbows at low incident energy and low surface temperature is attributed to multiple collisions with the surface. To study the role of these multiple collisions in the scattered distributions, classical trajectory simulations were performed. The rotational state distributions obtained by the simulation were in excellent agreement with the experimental data. Multiple collision trajectories play a large role in the dynamics at low incident energy and low surface temperature. The efficiency of energy transfer between N_2 and copper is attributed to the relative closeness of their masses. Measurements of N_2 scattering from silicon, which has the same mass as N _2, show even more efficient energy transfer and a higher trapping probability.