ARTICLE pubs.acs.org/JPCC
Initial Oxidation of Alkanethiol-Covered Copper Studied by Vibrational Sum Frequency Spectroscopy Saman Hosseinpour,† Jonas Hedberg,† Steven Baldelli,*,‡ Christofer Leygraf,† and Magnus Johnson*,† †
Department of Chemistry, Division of Surface and Corrosion Science, Royal Institute of Technology, Drottning Kristinas v. 51, SE-100 44 Stockholm, Sweden ‡ Department of Chemistry, University of Houston, Houston, Texas 77204-5003, United States ABSTRACT: The oxidation of octadecanethiol (ODT, CH3(CH2)17SH)-covered copper in dry air has been studied by in situ vibrational sum frequency spectroscopy (VSFS), infrared reflection absorption spectroscopy (IRAS), and cathodic reduction (CR). During the first 10 h of exposure, the VSF spectral line shape in the CH stretching region changed significantly, with resonances observed as dips being transformed into peaks. This was attributed to a phase change in the nonresonant sum frequency signal due to the formation of a thin layer of copper(I) oxide beneath the ODT. Complementary cathodic reduction and infrared reflection/absorption spectroscopy studies yielded a thickness of the oxide layer of
