Richard Williams

Reynolds Professor, Physics Dept., Wake Forest University

212 Olin Physical Laboratory
P.O. Box 7507
Winston-Salem, NC 27109-7507
Telephone: 336-758-5132
Fax: 336-758-6142




Ultrafast and Very Small:

Subpicosecond and Submicrometer Phenomena in Condensed Matter Physics // NSF DMR-9732023

We use ultrafast spectroscopy to investigate the immediate consequences of absorption of a photon by a crystalline solid. Ultrashort (~130 fs) high-power (~ 20 Gw) laser pulses are employed to create an electronic excitation of the solid and monitor its evolution within the coupled electron-lattice system. Phenomena of interest include self-trapping of excitons and of charge carriers in insulators, relaxation of hot carriers and surface state dynamics in semiconductors, and excitonic processes of lattice defect formation.  The onset of infrared absorption due to small electron polarons in lithium niobate is being investigated.  Nonlinear optical and ultrafast phenomena are studied in inhomogeneous samples and thin films with 3-dimensional spatial resolution of the order 200 nm x 700 nm using confocal multiphoton microspectroscopy.  Interactions at surfaces are investigated using ultrahigh vacuum analytical techniques such as fs time-resolved photoelectron spectroscopy.  Surface defects on CdSe are under investigation.   ZnO is a material of current interest for development of electronic and optical devices.  Thin film deposition and optical characterization are carried out in our laboratory.


Zinc Oxide:


Gang Xiong, John Wilkinson
at the pulsed laser deposition station
time-resolved spectroscopy
thin film deposition
giant oscillator strength


Recent Collaborative Projects

NATO supported a collaborative research program between the laboratory of Professor Williams and the Institute on Lasers and Information Technology of the Russian Academy of Sciences in Troitsk, Moscow region, directed by Academician Vladislav Ya. Panchenko. The project, from 1999-2003 investigated Multiwavelength Demultiplexers for High Bit-Rate Optical Communication Networks. Follow the NATO SfP link for more information.

Collaborations with University of Latvia and Estonian Institute of Physics

Self-Trapped Excitons in Complex Oxide Crystals

National Research Council Twinning Program with Latvia and Estonia on Self-trapped excitons in complex oxide crystals (1997-99) and continuing collaboration.

Research on Characterization of point defects and their spatial distributions in III-V semiconductors with 2001 visiting Fulbright Scholar Prof. Sebahattin Tuzemen.


Recent Publications

Graduate Students