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Motivated by a controversy about the proper interpretation of x-ray photoelectron spectra of Si/SiO2 interfaces derived from the adsorption of H8Si8O12 spherosiloxane clusters on Si(100) surfaces, we have studied the adsorption geometry of the H8Si8O12 clusters on deuterium-passivated and clean Si(100) surfaces by using external reflection infrared spectroscopy. Access to frequencies below 1450 cm−1 was made possible through the use of specially prepared Si(100) samples which have a buried metallic CoSi2 layer that acts as an internal mirror. A comparison of the infrared spectrum of the clusters on a deuterium-passivated Si(100) surface at 130 K with an infrared spectrum of the clusters in a carbon tetrachloride solution reveals that the clusters are only weakly physisorbed on the D/Si(100) surface and also provides evidence for the purity of the cluster source. We also present infrared spectra of clusters directly chemisorbed on a clean Si(100) surface and show evidence that the clusters are adsorbed on the Si(100) via attachment by one vertex. A complete assignment of the observed vibrational features, for both physisorbed and chemisorbed clusters, has been made based upon comparisons with the results obtained in ab initio calculations using gradient-corrected density functional methods.

Reproduction, in whole or in part, is permitted for any purpose of the United States Government.This document has been approved for public release and sale; its distribution is unlimited. 12 28 048 SREPORT DOCUMENTATION PAGEForm Approved II OMB No. 0704-0188 P•Joc' recr•t'-i uroen for this collection of information s •estimated to average I hour Oer response. including the time for reviewing instructliort . searching existing data sOurces gathe-ra and maintainrng the data needed, and completing and reviening the collection of information. Approved for public release; distribution is unlimited. ABSTRACT (Maximum 200 words)We report the first investigation of the adsorption of deuterium and water on diamond (100) by infrared multiple-internal-reflection spectroscopy using a natural type iHa diamond internal reflection element. Infrared evidence was seen for the monohydride surface structure, with one hydrogen atom per surface carbon atom (Sc1D mode at 901 cm-l), while the dihydride (CD2) structure was not observed. Following exposure to water at elevated temperature, infrared absorption features were detected at 1280, 1200, 1125, 1080, and 720 cm-1 , and are assigned to ether (C-O-C), hydroxyl (C-OH), and carbonyl (>C=O) modes. The substantial observed reactivity of diamond with water indicates a potentially important role for surface hydroxyl and oxide species in the surface chemistry and morphological development of CVD diamond films.14. AbstractWe report the first investigation of the adsorption of water on diamond (100) by infrared multiple-internal-reflection spectroscopy, using a natural type Ha diamond internal reflection element. Infrared spectroscopic results on the adsorption of atomic deuterium are also presented.