David Lynch Celebration
| Date/Time: | Monday, 07 Nov 2016 from 4:10 pm to 5:00 pm |
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| Location: | Phys 0003 |
| Contact: | Gloria Oberender |
| Phone: | 515-294-5441 |
| Channel: | College of Liberal Arts and Sciences |
| Actions: | Download iCal/vCal | Email Reminder |
Tai C. Chiang
During epitaxial growth and thermal processing of metal thin films on semiconductors, the system often self-organizes into domains or islands of preferred heights. This extra stability for specific thicknesses or heights has an electronic origin; confinement of the electrons in the film causes the formation of quantum-well states, which cross the Fermi level periodically as the film thickness increases. These periodic Fermi level crossings give rise to one-dimensional shell effects, akin to the shell effects associated with the periodic table. As a result, large variations in film properties are expected and observed, including the surface energy that determines the stability and preferred heights, the work function and other surface properties, and the superconducting gap and transition temperature. This talk will present highlights in recent advances on this subject, including angle-resolved photoemission measurements of the electronic structure and experimental and theoretical determinations of the amplitude, phase, period, and damping of the property variations. The effects of phonon scattering, including a recently discovered pseudogap feature in thin Pb islands, will be discussed.
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Franz J. Himpsel received his Diploma in Physics in 1973 at the University of Munich with a thesis in quantum electrodynamics under F. Bopp. After a summer at CERN/ISR he switched to condensed matter physics, working with W. Steinmann in Munich while using synchrotron radiation from DESY. After receiving his PhD in 1976/77 he joined D.E. Eastman at IBM Yorktown Heights for research in surface science with synchrotron radiation. He became staff member in 1980, manager in 1982, and senior manager in 1985, heading the Surface Physics Department. In 1995 he moved to the Physics Department of the UW Madison as full professor, where he also served as the Scientific Director of the Synchrotron Radiation Center (SRC) from 1997 to 2002. He became professor emeritus in 2015 but remains active in research.
Scientific Work:
His scientific interests have been in the area of surfaces and nanostructures. Utilizing his experience with synchrotron radiation he devised methods for mapping energy bands of solids and surfaces by angle-resolved photoemission. As complement he developed inverse photoemission with tunable photon energy for the study of unoccupied states. For identifying the bonding configurations at semiconductor surfaces/interfaces he took advantage of surface-sensitive core level spectroscopy with synchrotron radiation. Self-assembled nanostructures at surfaces have been a common thread throughout his career, such as magnetic quantum wells, atomic chains for the study of low-dimensional electrons, and an atomic scale memory for testing the limits of data storage. Most recently, he has ventured into the attachment of bio-molecules to surfaces and the design of new materials for solar cells. He has 480 publications in refereed journals and was listed among the 100 most-cited physicists.
Honors:
Fellowship by the German Studienstiftung as undergraduate and PhD student
Peter Mark Award of the American Vacuum Society 1985
Fellow of the American Physical Society 1985
Fellow of the American Vacuum Society 1994
Member of the New York Academy of Sciences in 1995
Ednor M. Rowe Professor of Physics 2000
Semiconductor Surfaces, Interfaces and Nanostructures Prize 2005, (ICFSI 2005)
Humboldt Research Award 2005
Davisson-Germer Prize of the American Physical Society 2007