Single-Molecule Spectroscopy, Photophysics of Nanostructured Semiconductors
Professor of Chemistry
Adjunct Professor of Physics
Senior Staff Scientist 2003-2004, Oak Ridge National Laboratory
Staff Scientist 1994 – 2003, Oak Ridge National Laboratory
PhD Rice University, 1991; BS California State University, Sonoma 1985
258 Goessmann Laboratory
Principal Research Interests
Our highly collaborative and interdisciplinary research explores the connection between structure and optoelectronic function in polymeric and inorganic composite nanostructures. Our experimental approach, termed “Chemical Microscopy,” combines single-molecule imaging and spectroscopy techniques along with scanning probe microscopies such as AFM, to understand details of structure and internal order in macromolecular systems and their relation photonic, or optoelectronic properties.
In collaboration with Prof. Todd Emrick (Polymer Science & Engineering), we are investigating the photophysics of individual composite quantum dot/conjugated organic nanostructures with the organic species linked directly to the quantum dot surface. Composite blended films of inorganic quantum dots (e.g. CdSe) and conjugated organic polymers (such as polyphenylene vinylene derivatives) have attracted significant recent interest for their unique optoelectronic properties and applications in energy harvesting devices. Our interest has been the connection between the degree of coverage and photophysical properties of the composite nanosystem. Our chemical microscopy studies on these species have revealed a rich and interesting single molecule photophysics that is closely coupled to the degree of surface coverage of the ligand.
In a separate joint project with the Venkataraman (DV) group at UMass, we are investigating the chemical microscopy of individual chiral molecules. While optical probes of chirality in molecular systems have been in place since the early 1800’s, conventional techniques such as optical rotatory dispersion or circular dichroism necessarily require the participation of a large number of molecules, thus obscuring information on the specific chiroptical signature for an individual molecule. Our research efforts (Hassey, et al., Science, 314, 1437 (2006)) have provided the first observation of the chiroptical response of chiral fluorophores in polymer-supported films and suggest new applications in chiroptical analysis of biofluorophores and novel display technologies.