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Charles B. Harris
Senior Faculty Scientist
Professor of Chemistry
University of California, Berkeley
Department of Chemistry
402 Latimer Hall
Berkeley, CA 94720-1460
USA
Chemical Physics Program
A Brief Bio
Charles B. Harris, born 1940; B.S. University of Michigan
(1963); Ph.D. Chemistry, Massachusetts Institute of Technology
(1966); Atomic Energy Commission Fellow in Physics and Chemistry,
Massachusetts Institute of Technology (1967); American Optical
Society Award in Applied Spectroscopy (1967); Jan van Guensfonds
Professor, University of Amsterdam (1973); Alfred P. Sloan
Fellow (1970-1972); Fellow of the American Physical Society
(1979); Alexander van Humboldt Fellow (1980); Miller Research
Professor, Berkeley (1984); Pittsburgh Spectroscopy Award
(1990); Member; Fellow of the Optical Society of America (1994);
Fellow of the American Academy of Arts and Science (1997);
Vice Chair of the Chemical Physics Division of the APS (1999);
Chair of the Chemical Physics Division of the APS (2000);
Former Member of the Advisory Boards: Journal of Chemical
Physics, Journal of Physical Chemistry and Molecular Physics,
Member of the American Chemical Society; Faculty Senior Scientist,
Chemical Sciences Division, Lawrence Berkeley National Laboratory.
Research Interests
Femtosecond lasers in the visible and
infrared are used to study energy transfer, relaxation, and
primary processes in chemical reactions in liquids and the
dynamical properties of electrons at interfaces and surfaces
on ultrafast timescales.
Research projects going on in the group are two-fold. They
include the study of the statistical or dynamical basis of
chemical reactions in condensed phase on the femtosecond time
scale and the dynamics and properties of electrons on surfaces
and at interfaces. Femtosecond lasers and ultrahigh vacuum
technology provide a unique opportunity to study the dynamics
of electrons at metal-dielectric and metal-semiconductor interfaces.
The femtosecond two-photon photoemission (TPPE) technique
utilizes a femtosecond pump pulse to excite electrons from
the metal substrate into states associated with the surface.
Photoemission of the surface electrons with a second femtosecond
pulse allows one to follow the various surface properties
in real time since the photoemission intensity as a function
of time delay between the pump and the probe pulse directly
reveals the dynamics of the surface electron population. Layer-by-layer
growth of dielectrics and large band gap semiconductors on
metal surfaces influences the binding energies, lifetimes,
and spatial distributions of electrons on surfaces and at
interfaces. Studies of Xe overlayers have shown the evolution
of metal surface states into quantum well states. Overlayers
of n-alkanes result in self-trapping of initially delocalized
electrons into localized small polarons. We have studied two
dimensional solvation of electrons interacting with nitrile
and alcohol overlayers on silver surfaces. Current studies
focus on extending our understanding of electronic structure
and dynamics to technologically important systems. In general
these methods enable us to study the dynamics of electrons
interacting with condensed matter in 2-D and how the properties
change as the system evolves into 3-D.
The second area, femtosecond infrared and ultraviolet and
visible spectroscopic methods are utilized to investigate
the dynamics of complex chemical reactions in solution. The
most basic reactions in solution share certain reaction processes,
which include dissociation, recombination, solvent caging,
molecular morphology changes, and system-solvent interaction.
These molecular events, which underlie our basic understanding
of reaction dynamics, occur on ultrafast (10-13-10-10 s) timescales.
Our research utilizes femtosecond experimental techniques
along with modern computational methods to study these fundamental
issues. The femtosecond infrared lasers developed in our group
enable us to study a variety of chemical systems in both the
time and spectral domain and as such we can follow elementary
chemical reaction events as they occur. There are also workstations
capable of carrying out large-scale, high-level quantum chemical
calculations and molecular dynamics (MD) simulations. Theoretical
methods including ab initio and density functional theory
(DFT) as well as MD are utilized to assist interpretation
and realization of experimental results. The combined experimental
and theoretical approach leads to a deeper understanding of
these fundamental processes. Not only do the results of these
studies address the issues outlined above, but they are also
of interest to researchers throughout the many subdisciplines
in chemistry including biological, organometallic, inorganic,
and organic chemistry.
In many instances the theoretical basis for the experiments
and observations must also be developed. As a result graduate
students from Professor Harris's group often obtain their
Ph.D. with a strong background in both theory and experiment.
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