Research Description

The Surface and Molecular Interface Group specializes in surface physics at the nanometer-scale in condensed phase systems. In practical terms: Can I build an electronic device out of a single molecule? Can I manipulate low-energy electrons on surfaces at the nanometer scale? Can I use the local nanometer-scale structure to direct surface chemistry? Insight into critical technological problems, such as molecular-scale electronics, molecular light-emitting diodes, light harvesting systems, and the environmental stability of surfaces relies on understanding fundamental chemical and physical processes at the nanometer scale. When a single molecule is placed between two electrodes, what is its electrical conductivity? How does light modify the molecule's electrical properties? How is chemical reactivity of molecules on surface influenced by the local environment, defects, etc.

Our current focus: STM images are more than pretty pictures, they contain a wealth of information that is generally overlooked. We are developing advanced real space image analysis techniques to extract this information. To gain a deeper understanding of our experiments, we supplement our measurements with simulations stating from molecular dynamics yielding simulated STM images and infrared spectra.

We use self-assembled monolayers (SAMs) as a matrix platform in which other molecules can be tethered. SAMs have the advantage that they can be easily prepared under bench-top conditions and their molecular components can be readily imaged by STM. In addition to STM, my group is also developing capability in in grazing angle-infrared spectroscopy for SAM characterization.

Our overarching goal is to understand the electronic and the optoelectronic characteristics of individual molecules and functional nanometer-scale assemblies. The experimental approach is to combine the molecular-scale resolution of scanning probe techniques, such as scanning tunneling microscopy (STM) and atomic force microscopy (AFM), with optical spectroscopy. Our group is also interested in developing novel scanning probe techniques.