个人简介

Dr. Petrich received his B.S. in Chemistry, cum laude, from Yale University in 1980 and his Ph.D. in Physical Chemistry from The University of Chicago in 1985. He went on to complete a postdoctoral fellowship at the Laboratoire d'Optique Appliquée, Ecole Polytechnique, Palaiseau, France, with Dr. Jean-Louis Martin. Dr. Petrich joined the Iowa State University faculty as an assistant professor in 1989. The following recognitions have been received by Dr. Petrich in the past few years for his work: ISU College of Liberal Arts and Sciences Award for Departmental Leadership, 2009. Fellow, American Association for the Advancement of Science, 2008. Secretary's Honor Award for Enhancing Protection and Safety of the Nation's Agriculture and Food Supply, U.S. Department of Agriculture, Washingtion, D.C., June 2004. Secretary's Honor Award (2004) for Enhancing Protection and Safety of the Nation's Agriculture and Food Supply and the ISU College of Liberal Arts and Sciences Mid-Career Award for Excellence in Research/Artistic Creativity. Agricultural Research Services Technology Transfer Award (2003). Award Honoring Iowa State University Inventors, April 29, 2002. 2002 Federal Laboratory Consortium Award for Excellence in Technology Transfer for work in Laser Detection in Food Safety, Little Rock, AK, May 8, 2002. Recognition of Food Safety Technology by the Iowa Department of Economic Development, Iowa da Vinci Celebration and Conference, February 2001. R&D 100 Award, 2000, "Method and System for Detecting Fecal and Ingesta Contamination on the Carcasses of Meat Animals". Finsen Award Lectureship, 2000 (Presented by the Association Internationale de Photobiologie and the American Society for Photobiology to an Outstanding Photobiology Researcher).

研究领域

Physical/Biophysical/Analytical Chemistry

Our research group uses light to study a range of fundamental and applied problems. We use and develop light-based techniques involving ultrafast lasers generating picosecond (10–12 sec) to femtosecond (10–15 sec) and steady-state sources. Our work involves extensive collaborations with other scientists both on and off campus. Three major areas of work involve: solvation dynamics, subdiffraction-limited imaging, and food safety. We are also entering the arena of developing alternate energy sources such as biofuels and photovoltaics. Solvation Dynamics. It is important for understanding the solvation process itself and for understanding how chemical reactions take place. We are interested in studying this “dynamic dielectric response” especially in proteins and in novel new solvents—room temperature ionic liquids. Consider a dye molecule dissolved in a solution or a protein. Before it absorbs a photon of light energy, its surroundings are oriented so as to produce the lowest energy interactions with respect to it. When the dye absorbs a photon of light, it experiences a change in its charge distribution—that is, the location of its electrons. The surroundings that were once oriented to minimize the energy of the system are no longer in such a position. In order to re-attain a minimum energy configuration, the surroundings must reorient. This is the dynamical dielectric response. The difference in energy between the vertically displaced curves is called the Stokes shift. By quantifying this Stokes shift and measuring how long it takes to occur, we can obtain important information on the function of proteins and solvents. The experimental techniques we most frequently use for these measurements are called fluorescence upconversion spectroscopy and time correlated single photon counting. Subdiffraction-Limited Imaging. Super-continuum (SC) stimulated emission depletion (STED) fluorescence lifetime imaging is demonstrated using time-correlated single-photon counting (TCSPC) detection. The spatial resolution of the developed STED instrument was measured by imaging monodispersed 40-nm fluorescent beads and then determining their FWHM, and was 36 ± 9 and 40 ± 10 nm in the X and Y coordinates, respectively. The same beads measured by confocal microscopy were 450 ± 50 and 430 ± 30 nm, which is larger than the diffraction limit of light due to under filling the microscope objective. Under filling the objective and time gating the signal were necessary to achieve the stated STED spatial resolution. The same fluorescence lifetime (2.0 ± 0.1 ns) was measured for the fluorescent beads using confocal or STED lifetime imaging. The instrument has been applied to study Alexa Fluor 594-phalloidin labeled F-actin-rich projections with dimensions smaller than the diffraction limit of light in cultured cells. Fluorescence lifetimes of the actin-rich projections range from 2.2 to 2.9 ns as measured by STED lifetime imaging. Food Safety. On the more applied side, we are interested in developing light-based real-time techniques for detecting contamination on food products or neurological diseases in animals and humans. We have recently found that by examining the fluorescence spectrum of the eye of a sheep or a cow, we can determine whether the animal is infected with a transmissible spongiform: scrapie or mad cow disease, respectively Fluorescence intensity of the retina from scrapie-negative and scrapie-positive sheep. Comparison of (a) scrapie-negative and (b) scrapie-positive sheep retinas at λex = 470 nm. Representative, front-faced fluorescence spectra from eight individual retinas are shown for each scrapie-negative and scrapie-positive animal. Note that the intensity values are in the same range for both data sets on the primary graphs. The inset graph for the scrapie-negative data uses an expanded ordinate. Significant differences of fluorescent intensity exist between the two data sets.

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Kee, T. W.; Adhikary, R.; Carlson, P. J.; Mukherjee, P.; Petrich, J. W. Femtosecond Fluorescence Upconversion Investigations on the Excited-State Photophysics of Curcumin. Aust. J. Chem. 2011, 64, 23-30. Bose, S.; Adhikary, R.; Barnes, C. A.; Fulton, B.; Hargrove, M. S.; Song, X.; Petrich, J. W. Comparison of the Dielectric Response Obtained from Fluorescence Upconversion Measurements and Molecular Dynamics Simulations for Coumarin 153-Apomyoglobin Complexes and Structural Analysis of the Complexes by NMR and Fluorescence Methods. J. Phys. Chem. A. 2011, 115, 3630-3641. Adhikary, R., Trampel R. L., Kee, T. W., Petrich, J. W., Cis-Trans Isomerization of Cyclocurcumin. J. Phys. Chem. B 2011, 115, 10707-10714. Zhao, L.; Pang, X.; Adhikary, R.; Petrich, J. W.; Lin, Z. Semiconductor Anisotropic Nanocomposites Obtained by Directly Coupling Conjugated Polymers with Quantum Rods. Angew. Chem. 2011, 50, 3958-3962. Zhao, L.; Pang, X.; Adhikary, R.; Petrich, J. W.; Jeffries-EL, M.; Lin, Z. Organic-Inorganic Nanocomposites by Placing Conjugated Polymers in Intimate Contact with Quantum Rods. Adv. Mater. 2011, 23, 2844-2849. Bose, S.; Barnes, C. A.; Petrich, J. W. Enhanced Stability and Activity of Cellulase in an Ionic Liquid and the Effect of Pretreatment on Cellulose Hydrolysis. Biotechnol. Bioeng. 2012, 109, 434-443. Carlson, P. J., Bose, S., Armstrong, D. W., Hawkins, T., Gordon, M. S., Petrich, J. W. Structure and Dynamics of the 1-Hydroxyethyl-4-amino-1,2,4-triazolium Nitrate (HEATN) High Energy Ionic Liquid System. J. Phys. Chem. B 2012, 116, 503-512. Nalwa, K. S.; Carr, J.; Mahadevapuram, R. C.; Kodali, H. K.; Bose, S.; Chen, Y.; Petrich, J. W.; Ganapathysubramanian, B.; Chaudhary, S. Enhanced charge separation in organic photovoltaic films doped with ferroelectric dipoles. Energy Environ. Sci. 2012, 5(5), 7042-7049. Lesoine, M. D.; Bose, S.; Petrich, J. W.; Smith, E. A. Supercontiuum Stimulated Emission Depletion Fluorescence Imaging. J. Phys. Chem. B. 2012, 116, 7821-7826. Barnes, C.A.; Rasmussen, S.L.; Petrich, J.W.; Rasmussen, M.A. Determination of the concentration of potential efflux pump inhibitors, pheophorbide a and pyropheophorbide a, in the feces of animals by fluorescence spectroscopy. J. Agric. Food Chem. 2012, 60, 10456-60. Lesoine, M.D.; Bhattacharjee, U.; Guo, Y.; Vela, J.; Petrich, J.W.; Smith, E.A. Subdiffraction, Luminescence-Depletion Imaging of Isolated, Giant, CdSe/CdS Nanocrystal Quantum Dots. J. Phys. Chem. C., 2013, 117 (7), 3662-3667.