Measurements of the work function of a Si(111) surface held at T20 K during exposure to O2 provide direct evidence for a precursor state preceding dissociative chemisorption. A striking feature of the precursor is its large surface dipole, resulting in a large positive work-function shift ( 1.6 eV). The precursor is effectively stable for T120 K, and converts to a final state upon heating the surface. Analysis of the dependence of on temperature and time indicates an activation energy of 40 meV for this conversion.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics