The Analytical and Surface Chemistry (ASC) program supports the research program of Prof. Steven Bernasek of the Department of Chemistry at Princeton University. Prof. Bernasek and his students will address fundamental questions of structure and reactivity in well characterized organic monolayers and thin films adsorbed on solid surfaces. They will examine the formation of organic monolayer structures, with particular emphasis on the formation of chiral monolayers, peptide oligomer monolayers, and nanopatterned surfaces, primarily using Scanning Tunneling Microscopy (STM). The project will provide fundamental information about the structure and reactivity of organic monolayers and thin films, which may help to answer questions about the development of chirality in living systems. Information from this work may be also useful in the design of chiral separations media and chirally active catalysts. The project will provide excellent training opportunities to students in an important research field of great interest to multiple industries.
Normal 0 false false false EN-US X-NONE X-NONE The goal of this research program was to develop an understanding of the effect of the structure of surface adsorbed layers on the subsequent dynamics of reactions occurring on the surface. This goal has been addressed in four specific, related projects. The first of these projects examined the functionalization of semiconductor surfaces using organic molecules. This work provides some of the fundamental underpinnings for the development of organic electronic devices and sensors. These devices take advantage of the structural and functional flexibility of organic molecules, using them, when attached to semiconductor substrates, as the active components in electronic devices and sensors. Our studies have identified conditions for the formation of particular structural layers, methods for attaching reactive molecules to the semiconductor substrate, and methods for controlling the geometry of adsorbed molecules that will serve as the functional components in these molecular scale devices. The second project, closely related to this first, addresses the fundamental driving forces and interactions that control the formation of particular structures when organic molecules interact with semiconductor or oxide surfaces. The balance of hydrogen bonding between adsorbed molecules and the van der Waals forces acting between them is found to control the formation of particular structures. Small differences in adsorbate molecule structure can have significant effects on the morphology and overall geometry of adsorbed layers. The interactions of these ordered, self-assembled, monolayers with reactive alkali metal atoms have also been explored, providing information relevant to the use of these structures in sensitive magnetic detectors important in advanced MRI methods. The third project extends the interaction of organic molecules with surfaces to the technologically challenging area of corrosion prevention and inhibition. The use of small molecule corrosion inhibitors is a cost effective approach for preventing or limiting corrosion in aggressive energy production environments. We have examined the mechanism of action of nitrogen containing heterocyclic molecules such as imidazole on the corrosion of mild steels in CO2 saturated brines. We have also seen and examined in detail the synergistic effect of small amounts of dissolved H2S in the CO2 saturated brines, in mitigating or enhancing corrosion inhibition by these nitrogen containing aromatic molecules.The systems studied here mimic the conditions in deep oil production wells, where corrosion is a crucial concern. The fourth related project addresses the use of X-ray photoelectron spectroscopy for the analysis of the composition of the monolayers and thin films studied in the previous three projects in this program. In this case, we have worked to develop electrical biasing of samples in the X-ray photoelectron spectrometer that allow us to compensate for charging in the organic layers, and to differentiate between components in these complex samples that have different charge transfer properties in the layer. Frequency dependent impedance spectroscopic measurements provide time dependent charge transfer information. This approach helps us to determine layer thickness and electrical properties directly, which is useful in analyzing these materials for organic electronic and sensor applications. These research projects have served as a training arena for advanced researchers in chemistry and materials science. Five postdoctoral research fellows received advanced research training in this program. Six graduate students have worked on their PhD dissertation examining the various aspects of the work described above. Two of these graduate students have completed their dissertations, and four are continuing to work on various aspects of this research. Eleven undergraduate research students have been involved in this research over the period of the program. Seven of these undergraduates have gone on to graduate study in chemistry or materials science. One has completed a law degree, and three are actively working in the chemical industry. Of the 22 coworkers involved in this research, eleven are female and two are members of an underrepresented minority group.
