Specific Research Areas
| I. |
Ultrafast
laser-induced dynamics in semiconductors: We use femtosecond
laser pulses to study highly non-equilibrium electron and lattice
dynamics in semiconductors. Ultrashort intense pulses excite
a large number of valence electrons into the conduction band,
while the lattice remains cold until sufficient time has elapsed
for the electrons to transfer their energy to the lattice. We
probe the evolution of the material following the excitation
with a resolution of 20-100 fs, about 10,000 times faster than
is possible with electrical measurements. When we excite about
10% of the valence electrons, we observe changes in phase and
in the bandstructure. With weaker excitations, we can study specific
carrier-carrier or carrier-phonon interactions. |
| II. |
Femtochemistry
at solid surfaces: We are interested in laser-induced chemical
reactions at solid surfaces. Currently, we are investigating
laser-assisted materials processing of semiconductors; we recently
discovered a novel way of microstructuring silicon with ultrashort
laser pulses. We are also interested in other chemical reactions
that take place at surfaces. At metal surfaces femtosecond laser
pulses can promote chemical reactions by exciting electrons in
the metal. Our overall goal is to understand the exchange of
energy between a substrate and reactant molecules. |
| III. |
Laser-induced
microexplosions: When intense femtosecond laser pulses are
focused inside a transparent material, the intensity in the focal
volume becomes high enough to cause absorption through nonlinear
processes. The pulse then produces microscopic permanent structural
change in the bulk of the material. Our goal is to characterize
the absorption and damage mechanisms and to explore applications
of our techniques in areas such as microsurgery, data storage,
waveguide and optical device fabrication, and
internal microstructuring of materials. |
| IV. |
Science
Education: We are studying methods for engaging students
in science courses, with a particular focus on interactive teaching
in large introductory courses and developing instructional technology
to facilitate these efforts. We are also studying gender issues
and the effectiveness of classroom demonstrations in introductory
physics courses. |
|
|
Group size
|
Graduate students |
Postdocs |
| |
Current |
Maximum |
Need in coming
6-12 months* |
Current |
| I. |
2 |
2 |
1 |
0 |
| II. |
2 |
2 |
1 |
0.5 |
| III. |
3 |
3 |
1 |
0 |
| IV. |
1 |
2 |
1 |
0.5 |
*This reflects growth, or changes
due to departures of the current students.
|