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Education and Training: University of Chicago Physics BA 1976 University of Illinois (Urbana) Physics MS 1977 University of Illinois (Urbana) Physics PhD 1983 Cornell University Applied Physics & postdoc, Materials Science 1983-85 Research and Professional Experience: Professor of Physics Purdue University 1998-present Visiting Professor, PULSE Institute SLAC (Stanford) Jan-Jun 2009 Associate Department Head Purdue University 2002-2005 Associate Professor of Physics Purdue University 1990-1998 Faculty Exchange Scholar Purdue/Hamburg 1992-1993 Assistant Professor of Physics Purdue University 1985-1990 Research Interests: Advanced synchrotron sources can now produce x-rays with enough energy per pulse to drive an absorbing material into highly excited states and to allow the study of ultrafast many body dynamics. We have used powerful undulator x-ray beams coupled with time-delayed optical laser pulses to explore excited state dynamics in GaAs and other materials. These x-ray and laser studies have revealed x-ray induced optical transparency, optical reflectivity, and even stimulated emission of band gap fluorescence. Other studies have uncovered interactions with long-lived metastable defect states in GaAs. X-rays from synchrotron sources have historically been used as non-perturbing probes of the structure of matter, or in laser pump/x-ray probe studies of dynamics. These results show the value of reversing the paradigm, i.e. the x-ray pump/laser probe technique.
