title: Adsorption configuration of sodium 2-quinoxalinecarboxylate on iron substrate: Investigation by in situ SERS, XPS and theoretical calculation.
abstract: The adsorption geometry of sodium 2-quinoxalinecarboxylate (2-QC) on iron surface was investigated by in situ surface-enhanced Raman scattering spectroscopy (SERS) and X-ray photoelectron spectroscopy (XPS) measurements. The density functional theory (DFT) calculations predicted that 2-QC ion was a highly efficient inhibitor and N as well as O atoms were the possible adsorption centers, and theoretically offered the Raman-active band position and intensity. Potential-dependent SERS results suggested that the 2-QC strongly bonded to the iron surface via the lone pair electrons of the two O atoms of the carboxylate group in a bidentate configuration with a vertical orientation at more positive potentials; However, at -1.0 V, only one O atom of the carboxylate and the neighboring N(1) atom (or very close to surface) adsorbed on the iron surface forming an unidentate configuration with a titled orientation. The ions did not remain on the iron surface at more negative potentials.
authors.affiliation: Department of Chemistry, College of Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, P. R. China. Electronic address: huoshengjuan@shu.edu.cn.
authors.forename: Sheng-Juan
authors.initials: SJ
authors.lastname: Huo
authors.affiliation: Department of Chemistry, College of Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, P. R. China.
authors.forename: Jin-Mei
authors.initials: JM
authors.lastname: He
authors.affiliation: Department of Chemistry, College of Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, P. R. China.
authors.forename: Li-Hong
authors.initials: LH
authors.lastname: Chen
authors.affiliation: Department of Chemistry, College of Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, P. R. China.
authors.forename: Jian-Hui
authors.initials: JH
authors.lastname: Fang
keywords: Iron; Sodium 2-quinoxalinecarboxylate; Surface-enhanced Raman scattering spectroscopy; Theoretical calculation; X-ray photoelectron spectroscopy