SLAC National Accelerator Laboratory
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Professor of Photon Science
BioHedman’s research program is focused on the development and applications of x-ray absorption and emission spectroscopies using synchrotron radiation, with a scientific emphasis primarily on study of the electronic and structural aspects of metal ion active sites in bioinorganic and biological systems. A common theme is to investigate how structure at molecular and macromolecular levels relates to function.
A major long-term focus has been the active site of the enzyme nitrogenase, and the various nitrogenase metal clusters, including elucidating the electronic and geometric structure of those that are formed and changed along their biosynthetic pathways. Other systems of systematic studies include iron-sulfur cluster containing enzymes, blue and multi-copper proteins, heme-copper oxidases, and iron-containing oxidases. Methods developments include x-ray absorption spectroscopy (edge and extended fine structure - or EXAFS), including the application of multiple-scattering analysis in EXAFS studies of metal clusters relevant to bioinorganic systems, the development of methodology for polarized single crystal x-ray absorption spectroscopy, and methodology and instrumentation development for soft- through hard-energy XAS.
Hedman received her B.S and B.A. in Chemistry, M.Sc. in Inorganic Chemistry, and Ph.D. in Chemistry from the University of Umeå, Sweden. She was Assistant Professor (equivalent) in Inorganic Chemistry at the University of Umeå before coming to Stanford, initially as Senior Academic Scientific Staff, followed by appointed as Professor (Research) in 2002, and Professor of Photon Science in 2007.
Professor of Applied Physics and of Photon Science and, by courtesy, of Electrical Engineering
Current Research and Scholarly InterestsElectronic properties and dynamics of nanoscale materials, ultrafast lasers and spectroscopy.
David Mulvane Ehrsam and Edward Curtis Franklin Professor of Chemistry and Professor of Photon Science at SLAC
BioCombining inorganic, biophysical and structural chemistry, Professor Keith Hodgson investigates how structure at molecular and macromolecular levels relates to function. Studies in the Hodgson lab have pioneered the use of synchrotron x-radiation to probe the electronic and structural environment of biomolecules. Recent efforts focus on the applications of x-ray diffraction, scattering and absorption spectroscopy to examine metalloproteins that are important in Earth’s biosphere, such as those that convert nitrogen to ammonia or methane to methanol.
Keith O. Hodgson was born in Virginia in 1947. He studied chemistry at the University of Virginia (B.S. 1969) and University of California, Berkeley (Ph.D. 1972), with a postdoctoral year at the ETH in Zurich. He joined the Stanford Chemistry Department faculty in 1973, starting up a program of fundamental research into the use of x-rays to study chemical and biological structure that made use of the unique capabilities of the Stanford Synchrotron Radiation Lightsource (SSRL). His lab carried out pioneering x-ray absorption and x-ray crystallographic studies of proteins, laying the foundation for a new field now in broad use worldwide. In the early eighties, he began development of one of the world's first synchrotron-based structural molecular biology research and user programs, centered at SSRL. He served as SSRL Director from 1998 to 2005, and SLAC National Accelerator Laboratory (SLAC) Deputy Director (2005-2007) and Associate Laboratory Director for Photon Science (2007-2011).
Today the Hodgson research group investigates how molecular structure at different organizational levels relates to biological and chemical function, using a variety of x-ray absorption, diffraction and scattering techniques. Typical of these molecular structural studies are investigations of metal ions as active sites of biomolecules. His research group develops and utilizes techniques such as x-ray absorption and emission spectroscopy (XAS and XES) to study the electronic and metrical details of a given metal ion in the biomolecule under a variety of natural conditions.
A major area of focus over many years, the active site of the enzyme nitrogenase is responsible for conversion of atmospheric di-nitrogen to ammonia. Using XAS studies at the S, Fe and Mo edge, the Hodgson group has worked to understand the electronic structure as a function of redox in this cluster. They have developed new methods to study long distances in the cluster within and outside the protein. Studies are ongoing to learn how this cluster functions during catalysis and interacts with substrates and inhibitors. Other components of the protein are also under active study.
Additional projects include the study of iron in dioxygen activation and oxidation within the binuclear iron-containing enzyme methane monooxygenase and in cytochrome oxidase. Lab members are also investigating the role of copper in electron transport and in dioxygen activation. Other studies include the electronic structure of iron-sulfur clusters in models and enzymes.
The research group is also focusing on using the next generation of x-ray light sources, the free electron laser. Such a light source, called the LCLS, is also located at SLAC. They are also developing new approaches using x-ray free electron laser radiation to image noncrystalline biomolecules and study chemical reactivity on ultrafast time scales.
Professor of Mechanical Engineering and of Photon Science
BioLarge-eddy simulation and modeling of turbulent reacting flows, non-premixed flame, aeroacoustics and combustion generated noise, turbulence and fluid dynamics, numerical methods and high-order schemes.
Director, Hansen Experimental Physics Laboratory (HEPL), Professor of Physics, of Particle Physics and Astrophysics and of Photon Science
BioIrwin Group web page:
Associate Professor of Chemical Engineering, of Energy Science Engineering and of Photon Science
BioRecent years have seen unprecedented motivation for the emergence of new energy technologies. Global dependence on fossil fuels, however, will persist until alternate technologies can compete economically. We must develop means to produce energy (or energy carriers) from renewable sources and then convert them to work as efficiently and cleanly as possible. Catalysis is energy conversion, and the Jaramillo laboratory focuses on fundamental catalytic processes occurring on solid-state surfaces in both the production and consumption of energy. Chemical-to-electrical and electrical-to-chemical energy conversion are at the core of the research. Nanoparticles, metals, alloys, sulfides, nitrides, carbides, phosphides, oxides, and biomimetic organo-metallic complexes comprise the toolkit of materials that can help change the energy landscape. Tailoring catalyst surfaces to fit the chemistry is our primary challenge.
Director of SLAC, Professor of Photon Science and Senior Fellow at the Precourt Institute for Energy
BioSLAC Director Chi-Chang Kao, a noted X-ray scientist, came to SLAC in 2010 to serve as associate laboratory director for the Stanford Synchrotron Radiation Lightsource. He became SLAC’s fifth director in November 2012.
Previously, Kao served for five years as chairperson of the National Synchrotron Light Source at Brookhaven National Laboratory in New York. He undertook major upgrades to the light source's scientific programs and experimental facilities while developing potential science programs for NSLS-II, one of the newest and most advanced synchrotron facilities in the world. His research focuses on X-ray physics, superconductivity, magnetic materials and the properties of materials under high pressure.
Kao earned a bachelor's degree in chemical engineering in 1980 from National Taiwan University and a doctorate in chemical engineering from Cornell University in 1988. He joined Brookhaven shortly afterward, working his way from NSLS postdoctoral research assistant to chair. Kao also served as an adjunct professor in the Department of Physics and Astronomy at Stony Brook University.
He was elected a fellow of the American Physical Society in 2006 and was named a fellow of the American Association for the Advancement of Science in 2010 for his many contributions to resonant elastic and inelastic X-ray scattering techniques and their application to materials physics, as well as for his leadership at the NSLS.