School of Humanities and Sciences
Showing 31-40 of 57 Results
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Fang Liu
Assistant Professor of Chemistry
Current Research and Scholarly InterestsThe group will develop scalable and controllable processes to produce low dimensional materials and their artificial structures, and unravel their novel static and dynamical properties of broad interest to future photonic, electronic and energy technologies. The topics will include: a) Unraveling time-resolved dynamics in light-induced electronic response of two dimensional (2D) materials artificial structures. b) Fabrication of 1D atomically thin nanoribbon arrays and characterization of the electronic and magnetic properties for the prominent edge states. c) Lightwave manipulation with 2D superlattices. These research projects will provide participating students with broad interdisciplinary training across physics, chemistry, and materials science.
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Thomas E. Markland
Professor of Chemistry
Current Research and Scholarly InterestsOur research centers on problems at the interface of quantum and statistical mechanics. Particular themes that occur frequently in our research are hydrogen bonding, the interplay between structure and dynamics, systems with multiple time and length-scales and quantum mechanical effects. The applications of our methods are diverse, ranging from chemistry to biology to geology and materials science. Particular current interests include proton and electron transfer in fuel cells and enzymatic systems, atmospheric isotope separation and the control of catalytic chemical reactivity using electric fields.
Treatment of these problems requires a range of analytic techniques as well as molecular mechanics and ab initio simulations. We are particularly interested in developing and applying methods based on the path integral formulation of quantum mechanics to include quantum fluctuations such as zero-point energy and tunneling in the dynamics of liquids and glasses. This formalism, in which a quantum mechanical particle is mapped onto a classical "ring polymer," provides an accurate and physically insightful way to calculate reaction rates, diffusion coefficients and spectra in systems containing light atoms. Our work has already provided intriguing insights in systems ranging from diffusion controlled reactions in liquids to the quantum liquid-glass transition as well as introducing methods to perform path integral calculations at near classical computational cost, expanding our ability to treat large-scale condensed phase systems. -
Todd Martinez
David Mulvane Ehrsam and Edward Curtis Franklin Professor of Chemistry and Professor of Photon Science
Current Research and Scholarly InterestsAb initio molecular dynamics, photochemistry, molecular design, mechanochemistry, graphical processing unit acceleration of electronic structure and molecular dynamics, automated reaction discovery, ultrafast (femtosecond and attosecond) chemical phenomena
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W. E. Moerner
Harry S. Mosher Professor and Professor, by courtesy, of Applied Physics
Current Research and Scholarly InterestsLaser spectroscopy and microscopy of single molecules to probe biological systems, one biomolecule at a time. Primary thrusts: fluorescence microscopy far beyond the optical diffraction limit (PALM/STORM/STED), methods for 3D optical microscopy in cells, and trapping of single biomolecules in solution for extended study. We explore protein localization patterns in bacteria, structures of amyloid aggregates in cells, signaling proteins in the primary cilium, and dynamics of DNA and RNA.
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Robert Pecora
Professor of Chemistry, Emeritus
Current Research and Scholarly InterestsThe development of the basic principles behind the dynamic light scattering (DLS) technique and its application to a wide variety of liquid systems is one of Pecora's outstanding contributions to physical chemistry. DLS is now an indispensable tool in the repertoire of polymer, colloid and biophysical chemists. It is generally accepted to be one of the best methods for measuring the mutual diffusion coefficients and, in dilute systems, the hydrodynamic sizes of polymers and particulates in solution or suspension. It is widely used, among other things, for studying size distributions of polymer and colloid dispersions; for testing theories of polymer dynamics in dilute and concentrated systems; and for studying interactions between macromolecules and colloidal particles in liquid dispersions. The basic work that established the foundation of this technique was done in the 1960s. Pecora has revisited this area over the years-formulating theories, for instance, of scattering from hollow spheres, large cylindrically symmetric molecules and wormlike chains.
An experimental program began in the early seventies resulted in a now classic series of studies on the rotational dynamics of small molecules in liquids. This work, utilizing mainly depolarized DLS and carbon 13 nuclear magnetic relaxation, has had a wide impact in the area of liquid state dynamics.
It was also during this period that the theoretical foundation for the fluorescence correlation spectroscopy technique (FCS) was formulated. Because of recent advances in equipment and materials, this technique has recently been revived and is now a powerful tool in biophysics.
The experimental and theoretical techniques developed for the study of the dynamics of relatively simple small molecule liquids have been used to investigate more complex systems such as the rotation of small molecule solvents in glassy and amorphous polymers. The resonance- enhanced depolarized light scattering technique was also developed in this period.
Extensive studies using depolarized dynamic light scattering (using the Fabry-Perot interferometer) as well as photon correlation spectroscopy, NMR, FCS and small angle X-ray scattering to the dynamics of oligonucleotides have determined the hydrodynamic diameter of DNA and the internal bending angles of the bases. They also provided support for relations relating hydrodynamic parameters to molecular dimensions for short rodlike molecules and “polyelectrolyte effects” on the translational and rotational motions of these highly charged molecules.
A major area of experimental and theoretical study has been the study of the dynamics of rigid and semirigid rodlike polymers in both dilute and semidilute dispersions. The work on translation and rotation of poly (-benzyl-L-glutamate) in semidilute solution is a foremost early work in this area.
The Pecora group has synthesized and studied the dynamics of model
rigid rod/sphere composite liquids. Studies of the translation of dilute spheres through solutions of the rods as functions of the rod and sphere sizes and the rod concentrations have provided the stimulus for more experiment and theoretical work in this area. Transient electric birefringence decay studies of the rotation of dilute rigid rod polymers in suspensions of comparably sized spherical particles have revealed scaling laws for the rod rotation.
A unique feature of part of this work on rigid and semirigid rodlike polymers is the utilization of genetic engineering techniques to construct a monodisperse, homologous series of DNA restriction fragments. These biologically-produced fragments have served as well-characterized model macromolecules for solution studies of the dynamics of semirigid rodlike polymers.
The well-regarded book of Pecora and Berne on dynamic light scattering, first published in 1976, has become a major reference work. It is now a Dover paperback. -
Alok Ranjan
Physical Science Research Scientist
BioAccomplished Research Scientist with a rich history (6-8 years) of spearheading cutting-edge research projects. Proficient in synthesizing and analyzing new compounds with therapeutic potential. Experienced in utilizing both structure and property-based strategies to identify promising drug candidates. Led multidisciplinary teams to innovate solutions, enhanced drug discovery efficiency by integrating advanced computational techniques. Committed to continuous learning and staying well-informed of the latest trends in medicinal chemistry and drug design.
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Jianghong Rao
Professor of Radiology (Molecular Imaging Program at Stanford) and, by courtesy, of Chemistry
Current Research and Scholarly InterestsProbe chemistry and nanotechnology for molecular imaging and diagnostics
