| AVS 63rd International Symposium & Exhibition | |
| Surface Science | Tuesday Sessions |
| Session SS1+AS+HC+NS-TuM |
| Session: | Surface Dynamics, Non-Adiabaticity, and Theory and Modeling of Surface and Interfacial Phenomena |
| Presenter: | Sean Casey, University of Nevada |
| Authors: | A.J. Pohlman, University of Nevada D.S. Kaliakin, University of Nevada S.A. Varganov, University of Nevada S.M. Casey, University of Nevada |
| Correspondent: | Click to Email |
Density functional theory and complete active space self-consistent field calculations were used to probe the thermal decomposition of alkyl radicals on the Si(100) surface. Single dimer and single row double dimer cluster models were used to mimic the Si(100) surface in the calculations, and results indicate an interdimer β-hydrogen elimination reaction is the kinetically favored thermal decomposition pathway for adsorbed alkyl radicals. This pathway occurs via a spin crossing from the initial singlet energy surface to the triplet surface mediated by spin-orbit coupling. On the triplet surface the barrier to the elimination reaction is predicted to be about 40 kJ/mol lower than on the singlet surface. Experimental thermal desorption studies of alkyl chlorides adsorbed onto the Si(100)-(2x1) surface appear to give desorption energies for alkene products that are consistent with the barriers computed for the interdimer β-hydrogen elimination spin accelerated reaction mechanism. Experimental and computational results for the adsorption/desorption energetics of several different alkyl radicals will be discussed, along with results from partial deuteration studies of adsorption of selected haloalkanes.