Angular distributions of H-induced HD and D 2 desorptions from the Si(100) surfaces

Abstract

We measured angular distributions of HD and D2 molecules desorbed via the reactions H+DSi (100) →HD [abstraction (ABS)] and H+DSi (100) → D2 [adsorption-induced-desorption (AID)], respectively. It was found that the angular distribution of HD molecules desorbed along ABS is broader than that of D2 molecules desorbed along AID, i.e., the former could be fit with cos2.0±0.2 θ, while the latter with cos5.0±0.5 θ. This difference of the angular distributions between the two reaction paths suggests that their dynamic mechanisms are different. The observed cos2 θ distribution for the ABS reaction was reproduced by the classical trajectory calculations over the London-Eyring-Polanyi-Sato potential-energy surfaces. The simulation suggests that the HD desorption along the ABS path takes place along the direction of Si-D bonds, but the apparent angular distribution is comprised of multiple components reflecting the different orientations of D-occupied Si dimers in the (2×1) and (1×2) double domain structures. © 2006 American Institute of Physics.