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SURFACE-ENHANCED RAMAN SCATTERING OF METHYLVIOLOGEN AT SILVER ELECTRODES AND ITS APPLICATION TO STUDY OF CHARGE TRANSFER AT THE SEMICONDUCTOR/ELECTROLYTE INTERFACE
Abstract
In Chapter 1, various techniques of surface analysis are briefy reviewed and compared. The application of surface-enhanced Raman scattering to the study of semiconductor electrodes is described. In Chapter 2, the UV-vis and Raman scattering spectroscopy of the reduced form of methylviologen (MV) is described in detail. Analysis of the UV-vis and Raman spectra of reduced forms of MV provides some information about the molecular configuration of this compound. Tentative assignment of absorption and Raman scattering bands is given. The Raman scattering of reduced MV on a silver electrode is surface-enhanced due to the adsorption of MV on silver surface. There are two kinds of interactions between MV and silver that give rise of two different surface-enhanced Raman spectra. Type I surface-enhanced Raman scattering is a result of usual chemisorption whereas Type II surface-enhanced Raman scattering may involve the chemical interaction between MV, silver and supporting electrolyte and formation of a complex. In Chapter 3, the charge transfer at an illuminated p-indium phosphide (p-InP)/methylviologen solution interface is studied by cyclic voltammetry and differential capacitance measurements. The open circuit potential of this system was found to be linearly proportional to the logarithm of light intensity. The photopotential, measured by comparing the cathodic peaks of MV$\sp{2+}$/MV$\sp{+}$ at Pt and illuminated p-InP electrodes, is a function of light intensity and solution concentration but not of wavelength. No evidence for a hot electron effect was found under the experimental conditions employed. The concept of quasi-Fermi level is used to explain the experimental results. In Chapter 4, the surface-enhanced Raman effect is employed to monitor the photoelectrochemically reduced methylviologen at a p-type InP electrode with a silver overlayer. The success of in situ monitoring of electrochemical reactions at p-InP electrode shows promise for the application of surface-enhanced Raman scattering to the study of semiconductor/electrolyte interfaces. The morphology of an effective silver island film was determined, and the film was found not to affect the photoresponse of the semiconductor electrode.
Subject Area
Analytical chemistry
Recommended Citation
FENG, QIAO, "SURFACE-ENHANCED RAMAN SCATTERING OF METHYLVIOLOGEN AT SILVER ELECTRODES AND ITS APPLICATION TO STUDY OF CHARGE TRANSFER AT THE SEMICONDUCTOR/ELECTROLYTE INTERFACE" (1987). ETD collection for University of Nebraska-Lincoln. AAI8800004.
https://digitalcommons.unl.edu/dissertations/AAI8800004