Thermoinduced and photoinduced reactions of NO on Si(111)7×7. III. Photoreaction mechanisms

The relative yield of photoinduced desorption from NO-exposed Si(111)7×7 has been measured as a function of photon power, wavelength, polarization, incident angle, and coverage of coadsorbed potassium. The results are analyzed in terms of two possible mechanisms: direct photoelectronic excitation of the NO-surface complex and interaction of hot carriers photogenerated in the substrate with the NO-surface complex. The substrate-mediated mechanism is found to be principally responsible for the photoreactions.