High-resolution photoemission study of ethanol on Si(100)2 x 1

The adsorption of ethanol on Si(100)2x1 has been investigated at room tempe rature by high-resolution synchrotron radiation photoemission, and a consis tent picture has been obtained in favour of dissociative adsorption, rom a comparison of the valence band for pure and adsorbed ethanol, which shows t he disappearance of sigma(O-H) orbital after adsorption, and from the ident ification of a Si-O-related component in the Si 2p core spectrum. A linesha pe analysis of the Si 2p complex envelope corresponding to different ethano l exposures identifies a second component, which grows with the exposure at a different rate, and is assigned to Si-H bond. The values for relative qu antitative ratios among the various components suggest an exposure-dependen t adsorption mechanism for ethanol, characterized by the formation of stabl e Si-O bonds and a high hydrogen surface mobility. The analysis of the C 1s photoemission core-line suggests that no C-O bond rupture occurs, at varia nce with our previous findings for ethanol adsorption on Si(111)7x7. (C) 20 00 Published by Elsevier Science B.V. All rights reserved.