AVS 53rd International Symposium
    Surface Science Tuesday Sessions
       Session SS2-TuM

Paper SS2-TuM9
Growth and Structure of Water on Amorphous SiO2 Investigated by Kelvin Probe Microscopy and In Situ X-ray Photoelectron Spectroscopy

Tuesday, November 14, 2006, 10:40 am, Room 2004

Session: Water-Surface Interactions
Presenter: M. Salmeron, Lawrence Berkeley National Laboratory
Authors: M. Salmeron, Lawrence Berkeley National Laboratory
A. Verdaguer, Institut Catala de Nanotecnologia, Spain
G. Ketteler, Lawrence Berkeley National Laboratory
Ch. Weiss, Lawrence Berkeley National Laboratory
H. Bluhm, Lawrence Berkeley National Laboratory
D.E. Starr, Lawrence Berkeley National Laboratory
Correspondent: Click to Email
The growth and structure of water layers on SiO2 on Si wafers at pressures between 1 and 4 torr and temperatures between -10 and 21 C has been studied using Kelvin Probe Microscopy and in situ X-ray photoelectron spectroscopy. As the relative humidity (RH) increases from 0 to 75% water adsorbs forming of a uniform film up to a thickness of 4 to 5 layers. The surface potential increases in that range by about 120 mV and remains constant afterwards. Above 75% RH the film grows rapidly reaching 6 to 7 monolayers at 90%. The near-edge X-ray adsorption spectra is similar to that of liquid water (imperfect H-bonding coordination) after the first four layers. At all stages the presence of unsaturated dangling H-bonds in the outermost layer in contact with the vapor is visible.