David Geohegan is currently a Research Thrust Leader in Laser Interactions and Optoelectronics at the Center for Nanophase Materials Sciences, and a member of the Materials Science and Technology Divisions at Oak Ridge National Laboratory (ORNL), and has served as an Adjunct Professor of the Department of Materials Science and Engineering at the University of Tennessee. He obtained his Ph.D. in Physics from the University of Illinois at Urbana-Champaign in 1986 on laser spectroscopy of atoms and molecules related to excimer laser kinetics. At ORNL, he has concentrated on understanding and controlling the synthesis of thin films and nanostructured materials through the development of time resolved laser spectroscopy and imaging diagnostic techniques. His research has more recently focused on carbon nanotube and nanohorn synthesis, purification, and processing into multifunctional materials. Basic science projects include studies of the fundamental growth mechanisms for nanomaterials, such as single-walled carbon nanotubes and nanohorns, nanoparticles, and nanowires as well as explorations of their functionality. His research utilizes lasers for synthesis, characterization, and processing of nanoscale materials which exhibit new nanoscale properties for use in hydrogen storage, solid state lighting, and other energy-related applications.
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David Geohegan (left) and Alex Puretzky capture digitized snapshots of a plasma plume caused by laser-vaporizing graphite. An intensified charge-coupled detector (ICCD) array camera is used to understand how the energy given to the carbon atoms and molecules in the plasma plume is redistributed to form novel new forms of carbon, such as amorphous diamond hard coatings, fullerene "buckyballs", and carbon nanotubes. Once interesting regions of the plume have been located, a variety of spectroscopic techniques (see at left) are applied to probe the plume at different positions and times. Similar techniques are applied to understand how thin films of high temperature superconductors are formed, or how silicon can be reformed into photoluminescent nanoparticles. Photograph by Tom Cerniglio |
Research Interests
Investigations of nanomaterials-synthesis
and thin film growth processes through the development and application
of in situ diagnostic techniques.
Carbon nanotube synthesis by laser vaporization and chemical vapor deposition
Pulsed Laser Deposition of thin films
Gas-phase nanoparticle formation
Multifunctional Carbon Nanotube
Composites 
Characterization of carbon nanotubes, and chemical processing into polymers and other matrices to make multifunctional nanotube-based composites – composite materials with enhanced properties and multiple functionalities. Characterization of electronic and thermal transport through nanotube-polymer composites. Alignment techniques of nanotubes in composites.
Fundamentals of laser interactions
with materials
Laser ablation and desorption.
Gas dynamics of laser-vaporized materials.
Contact Information
Dr. David B. Geohegan
1 Bethel Valley Road
MS-6056, Bldg. 3150
Oak Ridge, TN 37821-6056
(865) 576-5097 FAX: (865) 576-3676 Email: geohegandb@ornl.gov
