Non-activated pathway in angle-resolved study of H2 molecules produced in the abstraction reaction of incident H atoms on hydrogenated Si(1 0 0)

We present the first angle resolved study of H2 molecules coming from a hydrogenated Si(1 0 0)-2 × 1 surface at 650 K exposed to a chopped hydrogen atomic beam under fixed incidence angle. We get an exceptionally wide angular distribution, which can be fitted by cosn θ with n < 1. We interpret this new result by a non-activated pathway involving collision induced desorption and site-specific hot atom abstraction on two neighbor Si dimers inside a dimer row after passing through a transition state similar to the inter-dimer 4H reaction path, recently proposed in a H2/Si(1 0 0)-2 × 1 system.