Chemisorption of acetic acid onSi(100)−2×1at room temperature

Abstract

We have investigated adsorption of acetic acid on $\mathrm{Si}(100)\text{\ensuremath{-}}2\ifmmode\times\else\texttimes\fi{}1$ at room temperature using high-resolution photoemission spectroscopy and near edge x-ray adsorption fine structure (NEXAFS) measurements in the partial electron yield mode. At room temperature, an acetic-acid molecule is found to chemisorb on $\mathrm{Si}(100)\text{\ensuremath{-}}2\ifmmode\times\else\texttimes\fi{}1$ surface through the formation of the $\mathrm{O}\mathrm{H}$ dissociation structure. NEXAFS was conducted to characterize the adsorption geometry of acetic acid on Si(100). The ${\ensuremath{\pi}}^{*}$ orbital of the $\mathrm{C}\mathrm{O}$ bond shows a good angle dependence in carbon $K$-edge NEXAFS spectra, and we estimate the adsorption angle between chemisorbed acetic acid of $\mathrm{C}\mathrm{O}$ bond and the Si(100) surface normal as $\ensuremath{\sim}41\ifmmode^\circ\else\textdegree\fi{}\ifmmode\pm\else\textpm\fi{}2\ifmmode^\circ\else\textdegree\fi{}$ using an analytical solution of NEXAFS intensity.