Thermal, Photo- and Radiation-Induced Reactions in Condensed Media
This program examines
fundamental chemistry underlying production and efficient use of energy
stored in chemical forms, with focuses on chemistry of transient species
and catalysis.
The complementary techniques of excitation by photons or
fast electrons are used to 1) Provide basic knowledge relevant to the
capture and storage of light energy in useful chemical forms, and 2)
Elucidate the chemistry of radicals and ions on fast time scales.
Subjects investigated include electron transfer reactions, motions of
charges in condensed media (including fluids, ionic liquids, glasses and
supercritical fluids), fast molecular dissociation reactions,
dipole-moment changes in charge transfer transitions, formation of
excited states of molecules, transition metal complexes, and chemical
and physical transformations of excited and highly reactive species are
investigated. The
Laser-Electron Accelerator Facility (LEAF)
is a powerful tool for these studies.
The development of new
experimental techniques and detection systems at LEAF is an integral
part of our effort to produce ground-breaking science. Theoretical and
experimental efforts are elucidating the factors that control
excited-state lifetimes and electron transfer rates; the roles of
nuclear-configuration and free-energy changes, electronic configuration,
orbital symmetry, donor/acceptor separation, bridging groups and solvent
dynamics for a wide range of donor/acceptor systems.
The long-term storage of solar energy as fuels or valuable chemicals
requires efficient coupling of light absorption and chemical
transformations. Mechanistic studies of transition-metal complexes and
metal clusters which couple photo-induced electron transfer processes to
the bond-forming reactions required in the photogeneration of dihydrogen
and the photoreduction of carbon dioxide to carbon monoxide or methanol
are a major focus. Since M-H bond cleavage is a requisite step in both
catalytic and stoichiometric reactions of metal hydrides, a goal is an
improved understanding of the factors that influence the rates and
mechanisms for rupture of M-H bonds. This information contributes to
the rational design of new homogeneous catalysts and catalytic reactions
that are environmentally friendly, through use of alternative renewable
feedstocks, readily recycled catalysts, aqueous solvents, or
solvent-free processes.
The Thermal, Photo- and Radiation-Induced Reactions in Condensed Media Group
is supported by the
Photochemistry and Radiation Research Program of the
Division
of Chemical Sciences, Geosciences, and Biosciences of the
Office of Basic Energy
Sciences of the
Office of
Science under contract No. DE-AC02-98CH10886 with the
U.S.
Department of Energy.
Learn more about the Thermal, Photo-
and Radiation-Induced Reactions in Condensed Media Group
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Last Modified: January 31, 2008
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