Vibrational study of the metal–adsorbate interaction of phenylacetic acid and α-phenylglycine on silver surfaces

• Published in: Journal of colloid and interface science Vol. 263; no. 2; pp. 357 - 363
• Main Authors: Castro, J.L, López Ramı́rez, M.R, López Tocón, I, Otero, J.C
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 15-07-2003; Elsevier
• Subjects: Adsorption; Biophysical Phenomena; Biophysics; Carbon - chemistry; Chemistry; Exact sciences and technology; General and physical chemistry; Hydrocarbons - chemistry; Microscopy, Atomic Force; Models, Chemical; Phenylacetates - chemistry; Phenylacetic acid; Phenylglycine; Polymers - chemistry; Raman spectra; Solid-liquid interface; Steel - chemistry; Surface physical chemistry; Surface-Active Agents - chemistry; Surface-enhanced Raman spectroscopy; Temperature; Raman spectra; Phenylacetic acid; Surface-enhanced Raman spectroscopy; Phenylglycine; Liquid solid interface; Liquid solid adsorption; Transition metal; Acetic acid derivative; Glycine; Silver; α-Aminoacid; Molecular orientation; Carboxylic acid; Surface Enhanced Raman Spectrometry; Raman spectrometry; Charge transfer; Colloid particle
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/S0021-9797(03)00257-1

Raman and SERS spectra of phenylacetic acid and
α-phenylglycine on silver sols have been recorded at several concentrations and pH values. The
α-phenylglycine has been also studied in D
2O. The respective vibrational assignments have been proposed and the analysis of the SERS spectra has made it possible to conclude that phenylacetic acid links to the metal through its carboxylate group only, while
α-phenylglycine links also through its amino group. In both cases the aromatic ring seems to be almost perpendicular to the metal surface. On the other hand, the contribution of the charge transfer (CT) mechanism to the enhancement of the SERS spectra has been calculated as well and it is found to be very important in both molecules. The band most enhanced by this mechanism is that of vibration 8a, mainly in
α-phenylglycine.