Stereodynamics of surface chemical reactions on silicon

Okada, Michio*; Goto, Seishiro*; Hashinokuchi, Michihiro*; Moritani, Kosuke*; Teraoka, Yuden; Kasai, Toshio*

We have been developing a new machine of ultra-high-vacuum compatible oriented-molecular beam apparatus. We report results of a study on the incident-energy and the surface-temperature dependence of the steric effects in the dissociative adsorption of CHCl on an Si(100) surface. The initial sticking probability was measured by the King-Wells method. The data show that the initial sticking probability for the Cl-end collision is larger at an incident energy of 120 meV than that in the CH-end collision. Furthermore, this steric preference is quite sensitive to the kinetic energy and the rotational state and the surface temperature. This study shows that the non-equilibrium surface trapping plays a key role in the initial step of the decomposition. We also introduce the on-going experiments using a new apparatus for the reaction of oriented NO molecules with Si(111), we found that a N-end collision is more effective for the reaction than O-end collision.