Inelastic collision processes of CH4 and C2H6 molecules at highly corrugated surfaces studied by the molecular beam scattering technique

Inelastic collision dynamics of alkane (CH4 and C2H6) molecules at highly-c orrugated surfaces is studied by the molecular beam scattering technique. F or the azimuthal direction such as the [110] or the [100] of the impinging molecules on a LiF(001) surface, a wide variety of surface corrugation can be realized. Angular distributions of the reflected molecules realized in o ur experiment are found to qualitatively agree with those predicted by such simple classical collision models as hard cube [R. M. Logan and R. E. Stic kney, J. Chem. Phys. 44, 195 (1966)] and washboard [J. C. Tully, J. Chem. P hys. 92, 680 (1990)] models. The surface corrugation experienced by C2H6 mo lecules is found much less than that experienced by CH4 molecules, due to t he effectively large size of a C2H6 molecule. The surface corrugation decre ases as the kinetic beam energy of the impinging molecules increases. This is caused by the difference in energy dependence of the repulsive potential energy surface of Li and F ions which independently interact with the inco ming molecules. (C) 2000 American Institute of Physics. [S0021-9606(00)7112 2-6].