Integration of electrochemical methods with surface enhanced Raman spectroscopy, scanning tunneling microscopy, and atomic force microscopy

Electrochemical methods can be coupled with various experimental methods to apply to numerous areas of research. This body of work uses electrochemical methods in an interdisciplinary fashion towards the fields of Surface Enhanced Raman Spectroscopy (SERS), Scanning Tunneling Microscopy (STM) and Atomic Force Microscopy (AFM). In the SERS work, cyclic voltammetry is used to study the kinetic and spectroscopic profiles of pyridine complexes on silver at different potentials. Using Evolving Factor Analysis, it has been found that at the different potentials studied, there is evidence for the existence of three different silver/pyridine species at the electrode surface, rather than perhaps two as previously thought. With the Scanning Tunneling Microscope, cyclic voltammetry was used to study the diffusion of analyte to the tip area of the STM in a flow cell designed to image reactions as they take place on the substrate. Also, in order to counteract tunneling current interference and poor imaging caused by bulky or insufficient coating at the STM tip when imaging under a polar solution, a tip coating study that characterizes the relationship between tip coatings and solvents and determines the best tip coating for a particular solvent is included. In addition, electrochemical methods are used to monitor the behavior of alkanethiols on a gold surface and compare the electrochemical description of surface coverage to the observed coverage with the STM. Finally, work with conducting polymer nanostructures (polypyrrole and polythiophene) formed electrochemically on the step (natural) and pit (man-made) defects of highly ordered pyrolytic graphite is presented. By varying the amount of charge passed, their diameter and growth morphology can be controlled. Atomic Force Microscopy and optical microscopy are then used to examine the surface more deliberately, and in preparation for the use of a flowcell for imaging during polymerization. Optical microcopy illustrates the nucleation and growth of the polymer nanostructures, and AFM shows that nanostructures can be imaged nondestructively at resolutions comparable to STM, and without a tunneling current which would prevent imaging during deposition.