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Robert M. DicksonProfessor Office: MSE G209A Phone: 404-894-4007 Fax: 404-894-7452 |
B.A., Haverford College, 1991; Ph.D., University of Chicago, 1996.
NSF CAREER Award - 1999; Research Corporation Research Innovation Award - 1999; Alfred P. Sloan Research Fellow - 2001; Appointed as the Blanchard Assistant Professor of Chemistry - 2001; Camille Dreyfus Teacher-Scholar Award - 2002
Research Interests
Dr. Dickson's group is developing novel single molecule methods for the study of intermolecular interactions in biological and materials systems. By directly imaging anisotropic dipolar single molecule emission and modeling expected emission patterns, we have developed the world's only methods for determining true 3-D single molecule orientations. Since each molecule interacts differently with its surroundings, great diversity is observed in molecular behaviors. For example, single molecules in polymeric matrices exhibit surprising rotational mobilities that are indicative of nanoscale polymer dynamics. Such molecular orientational studies directly probe both biological and materials systems to provide greatly enhanced understandings of their dynamics.
Single Molecule Biophysics. Having observed orientation-dependent interactions of fluorescently labeled, single proteins, precise studies of biological mechanisms are performed. Unfortunately, standard fluorescent labels are often unsuitable for long-time single molecule imaging, especially in living systems. Thus, in order to make single molecule methods more accessible, we are developing Au and Ag nanoclusters as a new class of fluorescent labels in biology. These high brightness, robust nanomaterials should enable direct labeling of proteins to image live cells, study protein-protein interactions, and potentially watch individual proteins as they fold to their native conformations. Au and Ag nanoclusters exhibit discrete excitation and emission due to being composed of only a few atoms. Consequently, with size-tunable optical properties and absoprtion comparable to semiconductor quantum dots, but with improved photostability, these nanoclusters offer new opportunities in biological labeling. For example, the extremely small size will be less invasive; noble metals are not toxic; and their discrete energy levels enable energy transfer experiments to be performed—all with weak mercury lamp illumination on the single molecule level. Much brighter and more robust than organic dye molecules, these advanced inorganic nano-materials are being utilized both as optical memory elements and as photo-activated biological labels.
Molecules in Polymeric Environments. Single molecules in polymeric matrices exhibit surprising rotational mobility and spectral dynamics. Since each molecule interacts slightly differently with its surroundings, great diversity is observed in molecular behaviors. Photophysical properties of individual dyes are used to probe both random and enclosed structures to provide a better understanding of polymeric systems.
Single Molecule Electroluminescence. We have created the first electroluminescent single molecules/nanoclusters at room temperature. The discrete energy levels of these 2-20 atom nanoclusters yield molecular emission with color being indicative of nanocluter size. Employing negative differential resistance-like behavior in the EL, we have created single molecule LEDs, single nanocluster logic gates, and even a full adder constructed from only two nanoclusters. We are currently studying the charge injection into different nanoclusters to characterize the interfaces crucial to all nanoscale/molecular electronics and optoelectonics devices.
Recent Publications
C. M. Ritchie, K. R. Johnsen, J. R. Kiser, Y. Antoku, R. M. Dickson,
and J. T. Petty, "Ag Nanocluster Formation Using a Cytosine Oligonucleotide
Template", J. Phys. Chem. C, 111, 175 (2007).
J. Yu, S. A. Patel, and R. M. Dickson, "In vitro and Intracellular
Production of Peptide- Encapsulated Fluorescent Silver Nanoclusters",
Angew. Chem. Int. Ed. (2007) in press, published on web .
J. Zheng, P. R. Nicovich, and R. M. Dickson, "Highly Fluorescent
Noble Metal Quantum Dots", Annual Review of Physical Chemistry,
New Fluorescence Probes, 58, 409 (2007).
J. I. Gonzalez, T. Vosch, and R. M. Dickson, "Charged Injection
into Discrete States of Individual Electroluminescent Au Nanoclusters",
Phys. Rev. B, 74, 235404, (2006).
J. I. Gonzalez, T. Vosch, and R. M. Dickson, "Asymmetric Electrode-Molecule
Transport Dynamics Tracked by Nanoscale Electroluminscence", Phys.
Rev. B, 74, 064305, (2006).
T-H. Lee, J. Zheng, J. I. González, and R. M. Dickson "Single molecule optoelectronics", Accounts Chem. Res., 38, 534-541 (2005).
L. Peyser-Capadona, J. Zheng, J. González, T.H. Lee, S. Patel, R. Dickson "Nanoparticle-free single molecule anti-strokes raman spectroscopy" Phys. Rev. Lett., 94, 058301 (2005).
J. I. Gonzalez, T.-H. Lee, M. D. Barnes, Y. Antoku, and R. M. Dickson, "Nonclassical single gold nanocluster electroluminescent light source at room temperature", Phys. Rev. Lett., 93, 147402 (2004).
J. Zheng, C. Zhang, and R. M. Dickson, "Highly fluorescent, water-soluble, size-tunable gold quantum dots", Phys. Rev. Lett., 93, 077402 (2004).
T.-H. Lee and R. M. Dickson, "Nanocomputing with Nanocrystals", Optics and Photonics News, 15, 22-27 (2004).
J. T. Petty, J. Zheng and R. M. Dickson, "DNA Templated Ag Nanocluster Formation", J. Amer. Chem. Soc.,126, 5207-5212 (2004).
P. Kumar, T-H. Lee, R. M. Dickson, A. Mehta, B. G. Sumpter, M. D. Barnes, "Photon antibunching from oriented semiconducting polymer nanostructures", J. Amer. Chem. Soc., 126, 3376-3377 (2004).
T-H. Lee, R. M. Dickson, P. Kumar, A. Mehta, M. D. Barnes, "Photon antibunching from a single oriented semiconducting polymer nanostructure", Appl. Phys. Lett.85, 100-102 (2004).
T.-H. Lee, C. R. Hladik, and R. M. Dickson, "Facile, on-demand electronic nanodevice fabrication from photo and electro-active silver oxide", Appl. Phys. Lett., 84, 118-120 (2004).
T.-H. Lee and R. M. Dickson, "Single Molecule LEDs from Nanoscale Electroluminescent Junctions", J. Phys. Chem. B, 107, 7387-7390 (2003).
J. Zheng, J. T. Petty, and R. M. Dickson, "High Quantum Yield Blue Emission from Water-Soluble Au8 Nanodots", J. Amer. Chem. Soc., 125, 7780-7781 (2003).
T.-H. Lee, C. R. Hladik, and R. M. Dickson, "Asymmetric photoconductivity within nanoscale break junctions", NanoLett., 3, 1561-1564 (2003).
T.-H. Lee & R. M. Dickson, "Single Molecule LEDs from Nanoscale Electroluminescent Junctions", J. Phys. Chem. B, 107, 7387-7390 (2003).
J. Zheng, J. T. Petty, and R. M. Dickson, "High Quantum Yield Blue Emission from Water-Soluble Au8 Nanodots.", J. Amer. Chem. Soc., 125, 7780-7781 (2003).
T.-H. Lee and R. M. Dickson, "Discrete two-terminal single nanocluster quantum optoelectronic logic operations at room temperature", PNAS, 100, 3043-3046 (2003).
J. Zheng and R. M. Dickson, "Individual Water-Soluble Dendrimer-Encapsulated Silver Nanodot Fluorescence", J. Amer. Chem. Soc., 124, 13982-13983, (2002).
T.-H. Lee, J. I. Gonzalez, and R. M. Dickson, "Strongly Enhanced Field Dependent Single Molecule Electroluminescence", Proc. Nat. Acad. Sci. USA, 99, 10272-10275 (2002).
A. P. Bartko, K. Xu, and R. M. Dickson, "Three-dimensional single molecule rotational diffusion in glassy state polymer films", Phys. Rev. Lett., 89 026101/1-026101/4 (2002).
L. A. Peyser, A. E. Vinson, A. P. Bartko, and R. M. Dickson, "Photoactivated fluorescence from individual silver nanoclusters", Science, 2001, 291, 103-106.
Unidirectional Plasmon Propagation in Metallic Nanowires, R. M. Dickson and L. A. Lyon, J. Phys. Chem. B, 2000, 104, 6095-6098.
"Imaging three-dimensional single molecule orientations," A. P. Bartko, R. M. Dickson, J. Phys. Chem. B, 1999, 103, 11237-11241.
"Three-dimensional orientations of polymer-bound single molecules," A. P. Bartko, R. M. Dickson, J. Phys. Chem. B, 1999, 103, 3053-3056.
"Simultaneous imaging of individual molecules aligned both parallel and perpendicular to the optic axis," R. M. Dickson, et.al, Phys. Rev. Lett., 1998, 81, 5322-5325.
"On/off blinking and switching behaviour of single green fluorescent protein molecules," R. M. Dickson, et.al, Nature, 1997, 388, 355-358.
"Three dimensional imaging of single molecules solvated in the pores of polyacrylamide gels," R. M. Dickson, et.al, Science, 1996, 274, 966-969.