Semester

Summer

Date of Graduation

2000

Document Type

Dissertation

Degree Type

PhD

College

Eberly College of Arts and Sciences

Department

Chemistry

Committee Chair

Harry O. Finklea.

Abstract

Applications of the electrochemical method, AC Voltammetry (ACV), and its modifications based upon monitoring ac current as a function of ac potential modulation are described. The first chapter involves investigating the effect of a short peptide, melittin, on both hybrid bilayer membrane (HBM) dielectric properties and HBM resistance to heterogeneous electron transfer. These effects are discussed in terms of three possible mechanisms by which melittin may affect HBMs. In the second chapter, a modification of ACV, second harmonic ACV, is considered. A data processing method is suggested to analyze data collected at high perturbation frequencies at which the effect of uncompensated resistance cannot be neglected. In the third chapter, application of the spectroelectrochemical modification of ACV, Electrochemically Modulated Reflectance ACV, is discussed. The electromodulation reflectance coefficient, a ratio of ac electroreflectance to both DC electroreflectance and ac interfacial potential, is shown to be the most useful quantity to represent ac electroreflectance data. The same kinetic information on the surface faradaic reactions is available from electrochemical and spectroelectrochemical data. In the final chapter, ACV is applied to determine the rate of electron transfer kinetics for a redox couple attached via short alkanethiols (C5, C7, C 10) to a gold electrode. The semilog plot of standard rate constant vs. the number of methylene units remains linear down to the shortest used chain length (C5).

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