Photochemistry of N2O on Si(100), surface photo-oxidation

The oxidation of an Si(100) surface induced by photodissociation of adsorbe d N2O has been studied by X-ray photoelectron spectroscopy, temperature-pro grammed desorption, and angle-resolved time-of-flight (TOF) measurements. N 2O adsorbs in physisorption and chemisorption states on Si(100), The photoc hemical oxidation is induced by the irradiation of light in the wavelength range between 532 and 193 nm, The cross-sections of both adsorption states at 193 nm are larger than that of gaseous N2O by about two orders of magnit ude. Substrate-mediated excitation is considered to be responsible for the photochemistry of N2O in the two adsorption states. Although the TOF distri butions of N-2 fragments from the physisorbed N2O are almost identical in t he wavelength region studied, those from the chemisorbed N2O show a marked wavelength dependence. The interpretation is that there are multiple types of chemisorbed states whose photodissociation dynamics and the wavelength d ependence of the cross-section are different to each other. (C) 2000 Elsevi er Science B,V, All rights reserved.