Electrochemical and scanning probe microscopic characterizations of spontaneously adsorbed organothiolate monolayers at gold
A host of significant processes in the life and physical sciences (e.g., biological recognition, heterogeneous catalysis, corrosion, and mechanical lubrication) are controlled by interfacial architectures. The origins of many of these macroscopic interfacial processes are controlled by the molecular level interactions at condensed phase interfaces. The development of methods that can detect differences in the composition and orientational disposition of these architectures at high spatial resolution is therefore technologically important. With the invention and the development of a range of techniques commonly called scanning probe microscopy (SPM), probing details of the interfaces at a molecular length scale has now become a reality. SPM is extensively used in the field of organothiolate monolayers. The relatively convenient manipulation of surface architectures and control of the interfacial properties of the monolayers have allowed many variants of SPM to map the chemical distribution of surface functional groups, exploiting a range of interfacial properties (e.g., friction and adhesion) as contrast mechanisms at nanometer length scale. In an attempt to develop a better understanding of the monolayer formation process, the spatial distribution of differing chemical functional groups within the monolayer, and the orientation of the end-groups, this dissertation described the insights gained from SPM with those from macroscopic characterization techniques such as infrared spectroscopy, contact angle measurements, and electrochemistry. Four studies are presented. Common to the body of this work is the use of voltammetric reductive desorption and variants of SPM to gain insight into the nature of the monolayer formation process as well as the resulting interface.