Surface Chemistry Laboratory

Personnel:

Carrick Eggleston

Research:

The Earth's surface consists of trillions of square kilometers of mineral surface area. Chemical interaction between these mineral surfaces and water, air, and living things is the biggest single factor modulating and controlling the environment in which we all live. The Surface Chemistry Laboratory provides the instrumentation needed to study the fundamental chemistry that occurs at these interfaces. Minerals dissolve and grow, chemical species can adsorb to their surfaces, they catalyze various reactions, and they provide an electron transfer conduit. Partioning of material between solid, adsorbed, and dissolved form is fundamental to environmental chemistry and to understanding how Earth works.

The Surface Chemistry Laboratory features several scanning probe microscopes including scanning tunneling and atomic force microscopes as well as versions of these that operate at elevated temperature and pressure conditions. In addition to standard wet-chemical capabilities, we have instrumentation for synthesizing minerals films and for conducting electrochemical experiments. We also house several quite new techniques, including Optical Waveguide Lightmode Spectroscopy (OWLS) and Second Harmonic Generation (SHG). These techniques allow study of mineral-water interfaces, especially of adsorption processes, in-situ - that is, instead of removing samples to an instruments in which a vacuum is imposed so that we can study a surface (which can result in altering the surface as well), we specialize in techniques that allow us to study interface in their native environment, namely in water or air.

While much of what is discussed above sounds abiological, much of the recent work of the Surface Chemistry Laboratory has involved
microbiology. Specifically, we have conducted many electrochemical experiments with live bacteria and with functional electron transfer proteins; we have conducted protein adsorption and bacterial adhesion experiments, and we have conducted many microcial fuel cell experiments.

Capabilities:

• Scanning Tunneling Microscopy (STM) (Digital Instruments)
• Atomic Force Microscopy (AFM)
• Electrochemical STM and AFM
• Second Harmonic Generation (SHG) (10 Hz Nd:YAG laser, optical parametric oscillator for frequency tuning, and optics for second harmonic generation (SHG). SHG provides information about the mineral-water interface or the mineral-gas interface and supports fundamental research on chemical interactions between the materials of the Earth and their fluid surroundings (primarily water-rock interaction).
• Optical Waveguide Lightmode Spectroscopy (OWLS)
• Electrochemical Impedance Spectroscopy (EIS)
• Chemical Vapor Deposition (mass flow controllers, heating stages, etc.)