Robin Hochstrasser

faculty photo

Contact information
258N Chemistry 1973 Wing
231 South 34th Street
Philadelphia, PA 19104
Office: (215) 898-8410
Heriot-Watt University , 1952.
Edinburgh University , 1955.
Heriot-Watt University, Honoris causa , 1984.
Permanent link

Description of Research Expertise

A main focus is on the dynamics of structural change. Methods are sought that can determine the atomic level structure of molecules in the solution phase while they are undergoing conformational motions or chemical reactions. Such research involves nonlinear infrared spectroscopy and properties of single molecules. Femtosecond lasers are used to explore new linear and nonlinear properties of molecular systems. Processes such as electronic and vibrational energy transfer, electron and proton tunneling and phase relaxation in solids, ultrafast conformational processes in liquids and vibrational energy relaxation in condensed phases are studied. New laser techniques are also used to study protein dynamics, especially of peptides, small proteins, including those whose functions can be triggered by optical pulses. The research uses femtosecond pulsed lasers and high power tunable lasers for nonlinear studies. These and other modern techniques are used for studies of optical processes undergone by molecular systems of many types. An important goal is to bring the new experimental results into relationship with theory such as molecular dynamics simulations and quantum mechanics.

Two-Dimensional Infrared Spectroscopy

Infrared analogues of 2D NMR experiments are being developed in which the coupling between the vibrations mimics the coupling between the spins in NMR. Nonlinear spectroscopies such as the photon echo, facilitate experiments in which these couplings show up as cross peaks in a 2 D spectrum. The magnitudes of the couplings can be used to determine the structure of the network of vibrators giving rise to the signal.

Single Molecule Experiments

Imaging and fluorescence spectroscopy experiments on single molecules, proteins, assemblies of molecules and whole cells are carried out using modified forms of confocal microscopy. Recent work on the light harvesting complexes of photosynthesis, on protein folding and nucleic acid dynamics has shown structural effects that could not be observed from bulk experiments. A main topic of current research is conformational dynamics of single proteins. See RLBL homepage for more information.

Selected Publications

P. Hamm, and R. M. Hochstrasser: Structure and Dynamics of Proteins and Peptides: Femtosecond Two-Dimensional Infrared Spectroscopy. Ultrafast Infrared and Raman Spectroscopy. M.D. Fayer (eds.). New York: Marcel Dekker, Inc. Page: 273-348, 2001.

M. T. Zanni, M. C. Asplund and R. M. Hochstrasser: Two Dimensional Heterodyned and Stimulated Infrared Photon Echoes of N?methylacetamide-D. J. Chem. Phys. 114: 4579-90, 2001.

M. T. Zanni, and R. M. Hochstrasser: Two-dimensional infrared spectroscopy: a promising new method for the time resolution of structures. Curr. Opin. Struct. Biol 11: 516-22, 2001.

M. T. Zanni, S. Gnanakaran, J. Stenger and R. M. Hochstrasser: Heterodyned two-dimensional infrared spectroscopy of solvent dependent conformations of acetylproline-NH2. J. Phys. Chem 105: 6520-36, 2001.

M. C. Asplund, M. Lim and R. M. Hochstrasser: Spectrally Resolved Three Pulse Photon Echoes in the Vibrational Infrared. Chem. Phys. Lett. 323: 269-77, 2000.

P. Changenet-Barret, et al: Ultrafast Dielectric Response of Proteins from Dynamics Stokes Shifting of Coumarin in Calmodulin. J. Phys. Chem 104: 9322-29, 2000.

M. C. Asplund, M.T. Zanni and R. M. Hochstrasser: Two Dimensional Infrared Spectroscopy of Peptides by Phase Controlled Femtosecond Vibrational Photon Echoes. Proc. Natl. Acad. Sci. 97: 8219-8224, 2000.

D. S. Talaga , et al.: Dynamics and folding of single 2-stranded coiled-coil peptides studied by fluorescent energy transfer confocal microscopy. Proc. Natl. Acad. Sci. 97: 13021-29, 2000.

M. A. Bopp , et al.: The Dynamics of Structural Deformations of Immobilized Single Light Harvesting Complexes. Proc. Natl. Acad. Sci. 96: 11271-76, 1999.

P. M. Hamm, M. Lim, and R. M. Hochstrasser: The Structure of the Amide I Band of Peptides Measured by Femtosecond Nonlinear IR Spectroscopy. J. Phys. Chem 102: 6123-38, 1998.

back to top
Last updated: 08/31/2006
The Trustees of the University of Pennsylvania