The chemical oxidation of hydrogen-terminated silicon (111) surfaces in water was studied in situ with Fourier transform IR spectroscopy in the multiple total internal reflection mode. On the basis of measurements of the absorbance of the Si-H and Si-O-Si vibrations as a function of time it is concluded that reactions involving the oxidation of silicon hydride and the formation of silicon oxide are coupled. The decrease in the hydride coverage and increase in the oxide coverage are linear functions of ln(t). The time dependence of oxide growth is explained in terms of electrostatic and mechanical changes at the Si/water interface.
Fourier transform infrared multiple specular reflectance (FTIR-MSR) spectroscopy has been applied to study the chemisorption ofn-hexadecanoic or palmitic acid [CH3(CH2)14COOH] on aluminium as a function of surface coverage. The intensity of the symmetric carboxylate stretching vibration has been used to estimate the surface coverage. The intensities and band positions of the CH stretching modes are presented as a function of surface coverage. A sudden transition at about 80% of monolayer coverage is observed for the intensity as well as the position of the CH 2 stretching modes. The intensity changes correspond to a change from a more or less planar orientation of the polymethylene chains at low surface coverage to an almost perpendicular orientation at high surface coverage. The asymmetric CH 3 stretching vibration exhibits a shift opposite to and smaller than what is observed for the CH 2 vibrations. No significant changes are observed for the position of the symmetric CH 3 stretching vibration. However, for the symmetric carboxylate stretching vibration a sudden shift of the band position is observed of the same magnitude, but opposite to the shifts of the CH 2 vibrations.4926
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