Raymond L. Sobocinski

Surface enhanced Raman scattering in electrochemical systems: The complex roles of surface roughness

Abstract A series of experiments designed to elucidate the presence and properties of large-scale and atomic-scale roughness produced on Ag electrodes with electrochemical oxidation-reduction cycle (ORC) pretreatments are presented. This report reviews surface enhanced Raman scattering (SERS) and scanning electron microscopic (SEM) characterization of Ag electrodes roughened with controlled-rate ORCs, and presents new results for the laser-induced thermal decay of SERS as a probe of Ag surface active sites and differential reflectance spectroscopy of electrochemically roughened Ag electrodes. These results are interpreted in terms of the presence and properties of both large-scale and atomic-scale roughness on these surfaces.

The Effect of Charge Traps on Raman Spectroscopy Using a Thomson-CSF Charge Coupled Device Detector

Charge coupled device (CCD) detectors have seen increasing use in analytical spectroscopy in recent years. These detectors are optical array detectors based on silicon-metal oxide semiconductor technology. The basis of operation, the characteristics, and the modes of operation in a variety of analytical spectroscopies have recently been discussed in several excellent reviews by Denton and co-workers.

Raman spectroscopy of the emersed Ag | alcohol electrochemical interface

Abstract Raman spectroscopy is used to characterize the molecular structure and orientation of the solvent in electrochemical interfaces at Ag electrodes emersed from methanol and 1-propanol electrolyte solutions. The vibrational behavior of the solvent in the emersed interfaces is compared with that existing in situ as probed by surface enhanced Raman scattering as a function of electrode potential. Changes in peak frequency shifts and relative intensities as a function of potential are maintained upon emersion of the electrode from the alcohol electrolyte solution. These observations suggest that both solvent orientation and bonding environment at the Ag surface remain unperturbed by the emersion process. Additionally, the solvent behavior upon emersion is compared at rough and smooth Ag surfaces. The similarity in the spectra from these two types of surfaces as a function of potential suggests that surface enhanced Raman scattering can provide information about the average interfacial solvent molecules in electrochemical systems.

SERS investigation of interfacial Pb(II) species in weakly acidic aqueous halide media

Abstract Surface-enhanced Raman scattering (SERS) has been used to study surface adsorbates at Ag electrodes from weakly acidic Cl −1 and Br −1 solutions containing Pb(II). Spectra in the low-frequency region ( −1 ) indicate the presence of hydroxolead(II) complexes ionically bonded to specifically absorbed halide ions at the Ag surface. Studies of the effect of pH and halide ion concentration on the measured SERS intensities suggest that the surface precipitate has a composition in the ratio Pb(II):OH −1 :X −1 of 1:1:1. The underpotential deposition of Pb quenches the intensities of these bands at different rates as a function of Pb coverage. These results suggest contributions from chemical effects in SERS of these systems. Additionally, a band at 110 cm −1 grows in intensity as the first Pb monolayer is deposited on the Ag surface in Cl −1 media. This vibration is tentatively assigned as Pb-Pb stretch.