Surface-Enhanced Raman Spectroscopy (SERS) and Molecular Modeling of the Chromate Interaction with 4-(2-Mercaptoethyl)Pyridinium

Abstract

The interaction of 4-(2-mercaptoethyl)pyridinium (HMEP+) hydrochloride with chromate was investigated using surface-enhanced Raman spectroscopy (SERS) and molecular modeling. It was shown that HMEP+ on the gold surface attracted chromate to the SERS surface and that the adsorption of chromate onto the substrate is described by a Frumkin isotherm. The ion-pair constant for the chromate−HMEP+ interaction is more than 3 orders of magnitude larger than that measured for the HMEP+ interaction with perchlorate ion. The high selectivity of HMEP+ for chromate is attributed to hydrogen bonding between chromate and the HMEP+ moieties on the SERS surface.

Improved surface‐enhanced Raman scattering of polypyrrole electrodeposited on roughened substrates composed of Au–Ag bimetallic nanoparticles

“…3,4 Occurring on roughened metal substrates, SERS in principle provides a powerful means of obtaining vibrational information on adsorbate-surface interactions in view of its unique sensitivity and excellent wavenumber resolution. 5,6 Many techniques were used to obtain roughened metal substrates, including plasma treatment, 7 sputtering coating, 8 mechanically polishing by using abrasives, 9 vacuum evaporation deposition 10 and electrochemical and laser deposition. 11 However, a more controllable and reproducible surface roughness can be generated through the control of the electrochemical oxidation-reduction cycle (ORC) procedures.…”

Development of an Anion Probe: Detection of Sulfate Ion by Two-Photon Fluorescence of Gold Nanoparticles

“…40 A Frumkin-parameter expresses interactions between the adsorbed species. 38, 41 The positive value of g indicates an attractive force between adsorbed species. This seems strange in this case of anion adsorption to the cationic surface.…”

“…Mosier-Boss and Lieberman demonstrated the Frumkin type isotherm by a combination of the cationic self-assembled monolayer with an anion in solution with surface-enhanced Raman spectroscopy. 41,42 They reported negative g values and claimed that the adsorbed anion neutralized the surface charge electrostatically and decreased the attractive force working between the surface and the anion. However, in our results, the greater the sulfate ion adsorption, the more positive the surface of the AuNPs.…”

Improved surface-enhanced Raman scattering based on Ag–Au bimetals prepared by galvanic replacement reactions

“…In collecting Raman signals of organic compounds that are present in a system at very low concentration levels, SERS spectroscopy was employed to enhance the detection [5,6]. SERS occurring on roughened metal substrates, especially on silver, gold, copper and nickel, in principle provides a powerful means of obtaining vibrational information on adsorbate-surface interactions in view of its unique sensitivity and excellent frequency resolution [7,8]. In the general analytical applications for organic materials, nanoscale colloids [9,10] and metal-island films [11,12] are most used forms on SERS studies.…”