个人简介

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

研究领域

Physical Chemistry Single-Molecule Spectroscopy/Photophysics of Nanostructured Semiconductors

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.

近期论文

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S. E. Yalcin, B. Yang, J. Labastide, and M. D. Barnes, "Electrostatic Force Microscopy and Spectral Studies of Electron Attachment to Single Quantum Dots on Indium Tin Oxide Substrates," J. Phys. Chem. C, Just Accepted Manuscript (2012) M. D. Barnes, M. Baghgar "Optical probes of chain packing structure and exciton dynamics in polythiophene films, composites, and nanostructures," J. Polym. Sci. Part B: Polym. Phys., 50, (15) 1121–1129 (2012) M. Baghgar, J. Labastide, F. Bokel, I. Dujovne, A. McKenna, A. M. Barnes, E. Pentzer, T. Emrick, R. Hayward, and M. D. Barnes, "Probing Inter- and Intrachain Exciton Coupling in Isolated Poly(3-hexylthiophene) Nanofibers: Effect of Solvation and Regioregularity," J. Phys. Chem. Lett., 3, 1674–1679 (2012) A. Cyphersmith, S. Surampudi, M. J. Casey, K. Jankowski, D. Venkataraman, and M. D. Barnes, "Chiroptical Dissymmetries in Fluorescence Excitation from Single Molecules of (M-2) Helicene Dimers," J. Phys. Chem. A, 116 (22), 5349–5352 (2012) J. A. Labastide, M. Baghgar, I. Dujovne, Y. Yang, A. D. Dinsmore, B. G. Sumpter, D. Venkataraman, and M. D. Barnes, "Polymer Nanoparticle Superlattices for Organic Photovoltaic Applications," J. Phys. Chem. Lett., 2 (24), 3085–3091 (2011) S. E. Yalcin, J. A. Labastide, D. L. Sowle, and M. D. Barnes, "Spectral Properties of Multiply Charged Semiconductor Quantum Dots," Nano Lett., 11 (10), 4425–4430 (2011) J. A. Labastide, M. Baghgar, I. Dujovne, B. H. Venkatraman, D. C. Ramsdell, D. Venkataraman, and M. D. Barnes, "Time- and Polarization-Resolved Photoluminescence of Individual Semicrystalline Polythiophene (P3HT) Nanoparticles," J. Phys. Chem. Lett., 2 (17), 2089–2093 (2011) A. Cyphersmith, A. Maksov, R. Hassey-Paradise, K. D. McCarthy, and M. D. Barnes, "Defocused Emission Patterns from Chiral Fluorophores: Application to Chiral Axis Orientation Determination," J. Phys. Chem. Lett., 2 (6), 661–665 (2011) A. Cyphersmith, K. Early, A. Maksov, J. Graham, Y. Wang, and M. Barnes, "Disentangling the role of linear transition dipole in band-edge emission from single CdSe/ZnS quantum dots: Combined linear anisotropy and defocused emission pattern imaging," Appl. Phys. Lett. 97, 121915 (2010) K. T. Early, P. K. Sudeep, T. Emrick and M. D. Barnes, "Polarization-Driven Stark Shifts in Quantum Dot Luminescence from Single CdSe/oligo-PPV Nanoparticles," Nano Lett., 10 (5), 1754–1758 (2010) R. Hassey-Paradise, A. Cyphersmith, A. Tilley, T. Mortsolf, D. Basak, D. Venkataraman, M. D. Barnes, "Dissymmetries in fluorescence excitation and emission from single chiral molecules," Chirality , 21 (1E), E265-E276 (2009) M. Y. Odoi, K. T. Early, R. Tangirala, P. K. Sudeep, T. Emrick‡ and M. D. Barnes, "Probing Multiexcitonic Emission in Single CdSe−Oligo(phenylenevinylene) Composite Nanostructures," J. Phys. Chem. C, 113 (31), 13462–13465 (2009) K. T. Early, K. D. McCarthy, M. Y. Odoi, P. K. Sudeep, T. Emrick and M. D. Barnes, "Linear Dipole Behavior in Single CdSe-Oligo(phenylene vinylene) Nanostructures," ACS Nano, 3 (2), 453–461 (2009)