Stereodynamics of chemical reactions in heterogeneous systems; Dissociative adsorption of NO on Si(111)

Hashinokuchi, Michihiro*; Okada, Michio*; Ito, Hironori*; Kasai, Toshio*; Moritani, Kosuke*; Teraoka, Yuden

We present the steric effect recently observed in the dissociative adsorption of NO on Si(111)-77 surface by using an oriented-molecular-beam apparatus especially designed for X-ray photoelectron spectroscopy. The (1/2,1/2,1/2) state-selected NO molecular beam with the kinetic energy of 58 meV was incident to Si(111) surface and adsorbed species were analyzed by XPS. We find that the reaction is more favorable for the N-end than that for the O-end. The steric preference becomes very small at 600K. This result shows that transient trapping into a shallow precursor state plays the key role in the stereodynamics of this surface reaction.