Thioglycolic acid on the gold (111) surface and Raman vibrational spectra Jian-Ge Zhou $^{a}$, Quinton L. Williams$^{a}$, Ruqian Wu$^{b}$, $^{a}$Department of Physics, Atmospheric Sciences, and Geoscience, Jackson State University, Jackson, MS 39217, USA $^{b}$Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA The interaction of thioglycolic acid (HSCH$_{2}$COOH) with the Au(111) surface is investigaged, and it is found that at the low coverage the molecule lies down on the substrate. If the mercaptan- hydrogen atom is eliminated, the resulting SCH$_{2}$COOH molecule is randomly oriented on the surface. If the carboxylic acid group in the HSCH$_{2}$COOH molecule is deprotonated instead, the HSCH$_{2}$COO − molecule lies down on the surface. However, when the mercaptan-hydrogen atom in the HSCH$_{2}$COO − molecule is removed, the resulting SCH$_{2}$COO − molecule rises up to a certain level on the substrate. The calculated Raman vibrational spectra decipher which compounds and atomic displacements contribute to the corresponding frequencies. We thus propose a consistent mechanism for the deposition of thioglycolic acid on the Au(111) surface. PACS numbers: 68.43.Bc, 61.43.Bn, 73.20.Hb arXiv:1002.1301v1 [cond-mat.mtrl-sci] 5 Feb 2010 1 Abstract