Michael D. Fayer
Research Accomplishments
Mike Fayer For many years, Professor Michael D. Fayer has been a world leader in the development and application of ultrafast non-linear laser techniques and associated theory to the study of molecular condensed matter systems. In large part due to his work, ultrafast nonlinear and coherent spectroscopic techniques such as transient gratings, photon echoes, and vibrational echoes are now used widely, and have become powerful techniques for studying fast molecular processes, intermolecular interactions, and structure in complex molecular systems. Fayer is currently applying ultrafast infrared and visible methods to the study of hydrogen bonding liquids, supercooled liquids, liquid crystals, micelles and reverse micelles, electron transfer, and proteins.
Fayer has continually maintained world leadership in the development of nonlinear and coherent spectroscopic techniques and instrumentation, and in his landmark studies of optical dephasing, electronic energy transport, electron transfer, and vibrational dynamics. His work has had a profound impact on modern physical chemistry and has led to the establishment of a school in which his methods and approaches to the examination of physical chemical problems have spread worldwide. His former students, post docs, and visiting scholars, who are at many top universities in the US, and many top institutions around the world, continue the experimental and theoretical work originated at Stanford, in every area of modern condensed matter physical chemistry.
In the late 1970’s, Fayer began decades of development of the transient grating technique, which has now become the most widely used NLO technique in chemistry, to measure dynamical phenomena in molecular systems. The high spatial resolution has been exploited to measure the interactions of chromophores with tunable phonons with specifically chosen wave vectors, anisotropic diffusion in lipid bilayers, the velocity distribution of atoms in flames, and phonons in diamond, high Tc superconductors and thin films. Optical Kerr-effect gratings have been used to study the mechanical dynamics of complex fluids. For the first time dynamics on all time scales—from sub picosecond ballistic motion to picosecond molecular reorientation to microsecond and slower local domain reorientation and translational diffusion--have been completely characterized and used as a critical tests of theoretical predictions.
Fayer’s photon echo experiments were the first to explicate the relationship between optical dephasing and hole burning in amorphous materials. For many years, researchers worldwide believed that hole burning measured the homogeneous linewidth. Fayer showed that photon echoes gave narrower linewidths than hole burning. In 1987, Fayer definitively demonstrated that hole burning linewidths could be as much as an order of magnitude greater than the homogeneous linewidth from photon echoes by simultaneous temperature-dependent hole burning and echo experiments on the same samples. The increased linewidth in hole burning is caused by structural evolution occurring on the long time scale associated with the hole burning experiment. This work has become the basis of a new field, where the structural dynamics of amorphous and biological materials are characterized over time ranging from picoseconds to hours.
In electronic energy transfer and electron transport, exact expressions are known for the transfer rate from a donor to an acceptor at a fixed distance from the work of Förster and Marcus. That knowledge alone is not enough to explain charge or excitation migration in random media with many donors and acceptors. For example, Förster attempts to calculate the diffusion coefficient for energy diffusion on various lattices was incomplete in that the short time dynamics are not diffusive. A breakthrough occurred in 1979, when Fayer, Gochanour and Andersen developed the first infinite-order many-body treatment of electronic energy transport in disordered media. Subsequently, Fayer’s group developed accurate techniques for calculating transport in infinite media, finite-volume media, media with dynamic diffusion, crystal lattices, and so on. Combined with extremely sensitive measurements using gratings and other ultrafast techniques, Fayer has explained the structural and dynamic effects which govern electron and energy transport in molecular media. The energy transport work has been used to observe the aggregation of as few as two polymer chains in a polymer blend, which defines the onset of phase separation. In photoinduced electron transfer with random donors and acceptors in liquids, Fayer showed that forward transfer is characterized by a complex rate expression involving the solvent radial distribution function to account for the distance distributions of donors and acceptors. Back transfer (geminate recombination) rates involve the spatial correlation with the donor, and a time-varying dielectric constant to account for donor and acceptor diffusion in a time-varying Coulomb potential produced by the transferred electrons. Fayer’s work is the most important and original contribution in these areas since Förster and Marcus.
Ten years ago, Fayer performed the first ultrafast vibrational echo experiments and has recently extended these to multidimensional approaches. Vibrational echoes are the vibrational analog of the spin echo technique, the first significant development in pulsed NMR technology. Originally these experiments could be done only with super conducting free-electron lasers (FELs). Fayer’s FEL work galvanized the world’s FEL community to develop new lasers optimized for molecular research. Advances in tunable femtosecond IR technology have now allowed the vibrational echo work to be done on a tabletop. A combination of pump-probe and vibrational echo measurements was used by Fayer to explain the vibrational line shapes of molecules in liquids and glasses for the first time, including a direct demonstration that vibrational transitions of molecules in ambient liquids can be inhomogeneously broadened. In contrast to photon echoes, which have limited applicability at other than very low temperatures, vibrational echoes can be used on complex systems and biological molecules even at room temperature. Fayer has demonstrated that vibrational echoes can be used to directly probe protein structural fluctuations on the picosecond time scale and the temperature dependence of protein dynamics has been used to demonstrate the intrinsic glassy behavior of proteins. Very recently, Fayer has extended the ultrafast infrared vibrational echo method to perform Vibrational Echo Correlation Spectroscopy measurements with full phase information. These methods as well as other multi-dimensional techniques are greatly extending the types of questions that can be asked and answered concerning complex molecular systems. Recent experiments examine water dynamics and the dynamics of nanoscopic water in reverse micelles. In addition, fundamentally new information is being obtained about protein dynamics and structure. In addition infrared methods, the Fayer groups application of ultrafast to slow optical heterodyne detected optical Kerr effect experiments to supercooled liquids and liquid crystals are making fundamental changes the understanding of the relationship between dynamic and structure in these important systems.
Recent Representative Publications
“Structural Assignments and Dynamics of the A Substates of MbCO: Spectrally Resolved Vibrational Echo Experiments and Molecular Dynamics Simulations,” Kusai A. Merchant, W. G. Noid, David E. Thompson, Ryo Akiyama, Roger F. Loring, and M. D. Fayer, J. Phys. Chem. B 107, 4-7 (2003).
“Short Time Dynamics in the Isotropic Phase of Liquid Crystals: the Aspect Ratio and the Power Law Decay,” Hu Cang, Jie Li, and M. D. Fayer, Chem. Phys. Lett. 366, 82-87 (2002).
"Isomerization and Intermolecular Solute-Solvent Interactions of Ethyl Isocyanate: Ultrafast Infrared Vibrational Echoes and Linear Vibrational Spectroscopy,” Nancy E. Levinger, Paul H. Davis, Pradipta Behera, D. J. Myers, Christopher Stromberg and M. D. Fayer, J. Chem. Phys., 118, 1312-11326 (2003).
“Orientational Relaxation and Vibrational Excitation Transfer in Methanol - Carbon Tetrachloride Solutions,” K. J. Gaffney, I. R. Piletic, and M. D. Fayer, J. Chem. Phys., 118, 2270-2278 (2003).
“Experimental Observation of Nearly Logarithmic Decay of the Orientational Correlation Function in Supercooled Liquids on the Ps to Ns Time Scale,” Hu Cang, V.N. Novikov, and M. D. Fayer, Phys. Rev. Lett. 90, 197401 (2003).
“Dynamics in Supercooled Liquids and in the Isotropic Phase of Liquid Crystals: A Comparison,” Hu Cang, Jie Li, V.N. Novikov, and M. D. Fayer, J. Chem. Phys., 118, 9303-9311 (2003).
“Structural Dynamics of Hydrogen Bonded Methanol Oligomers: Vibrational Transient Hole Burning Studies of Spectral Diffusion,” I. R. Piletic, K. J. Gaffney, and M. D. Fayer, J. Chem. Phys. 119, 423-434 (2003).
“Hydrogen Bond Dynamics Probed with Ultrafast Infrared Heterodyne Detected Multidimensional Vibrational Stimulated Echoes,” John B. Asbury, Tobias Steinel, C. Stromberg, K. J. Gaffney, I. R. Piletic, Alexi Goun, and M. D. Fayer, Phys. Rev. Lett. 91, 237402-1 – 237402-4 (2003).
“Hydrogen Bond Breaking Probed with Multidimensional Stimulated Vibrational Echo Correlation Spectroscopy,” John B. Asbury, Tobias Steinel, C. Stromberg, K. J. Gaffney, I. R. Piletic, and M. D. Fayer, J. Chem. Phys. 119, 12981-12997 (2003).
“Myoglobin-CO Substate Structures and Dynamics: Multidimensional Vibrational Echoes and Molecular Dynamics Simulations,” Kusai A. Merchant, W. G. Noid, Ryo Akiyama, Ilya Finkelstein, Alexei Goun, Brian L. McClain, Roger F. Loring, and M. D. Fayer, J. Am. Chem. Soc. 125, 13804-13818 (2003).
“Using Ultrafast Infrared Multidimensional Correlation Spectroscopy to Aid in Vibrational Spectral Peak Assignments,” John B. Asbury, Tobias Steinel, M. D. Fayer, Chem. Phys. Lett. 381, 139-146 (2003).
“Hydrogen Bond Networks: Structure and Evolution After Hydrogen Bond Breaking,” John B. Asbury, Tobias Steinel, and M. D. Fayer, J. Physical Chemistry B 108, 6544-6554 (2004).
“Dynamical Signature of Two “Ideal Glass Transitions” in Nematic Liquid Crystals,” Hu Cang, Jie Li, V.N. Novikov, and M. D. Fayer, J. Chem. Phys. 119, 10421-10427 (2003).
“Orientational Dynamics of the Ionic Organic Liquid 1-Ethyl-3-Methylimidazolium Nitrate,” Hu Cang, Jie Li, and M. D. Fayer, J. Chem. Phys. 119, 13017-13023 (2003).
“Water Dynamics: Vibrational Echo Correlation Spectroscopy and Comparison to Molecular Dynamics Simulations,” John B. Asbury, Tobias Steinel, C. Stromberg, S. A. Corcelli, C. P. Lawrence, J. L. Skinner, and M. D. Fayer, J. Phys. Chem. A 108, 1107-1119 (2004).
“Water Dynamics: Dependence on Local Structure Probed with Vibrational Echo Correlation Spectroscopy,” Tobias Steinel, John B. Asbury, S. A. Corcelli, C. P. Lawrence, J. L. Skinner, and M. D. Fayer, Chem. Phys. Lett. 386, 295-300 (2004).
“Photoinduced Electron Transfer and Geminate Recombination for Photoexcited Acceptors in a Pure Donor Solvent,” V. O. Saik, A. A. Goun and M. D. Fayer, J. Chem. Phys. 120, 9601-9611 (2004).
