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Gas Phase Chemical Physics Program
Stephen R. Leone
William A. Lester, Jr.
William H. Miller
LBNL’s Gas Phase Chemical Physics Program performs basic research that helps to build the nation’s knowledge of combustion, currently the most important overall energy source. The engineering challenges associated with achieving cleaner and more efficient combustion are immense.
The GPCP program develops and employs experimental techniques and theoretical methods that can be applied in order to bring clearer understanding of elementary reactions and reactive intermediates in combustion chemistry.
Our Spectroscopy and Dynamics of Free Radicals project continues the development and application of state of the art laser-based experiments that probe fundamental properties of radicals. The program is widely recognized for pioneering designs, such as negative ion photodetachment.
Schematic of anion SEVI instrument.
A diverse approach to researching combustion chemistry is taken by applying a variety of experimental techniques to study radical spectroscopy and dynamics. We characterize key properties of free radicals including bond dissociation energies, orbital energetics, electron affinities, spectroscopy of low-lying electronic states, primary photochemistry, and reaction dynamics. Laser spectroscopic methods and vacuum ultraviolet (VUV) light from the Chemical Dynamics Beamline of the Advanced Light Source are used to selectively investigate individual processes involved in formation and reaction of radicals. In conjunction with our theory efforts, these studies facilitate a detailed understanding of the role of free radicals in reaction mechanisms that govern diverse processes such as low-temperature autoignition, the oxidation of aromatic hydrocarbons, and the growth of complex molecules such as polyaromatic hydrocarbons in flames.
Our Theory of Electronic Structure and Chemical Dynamics projects develop theoretical methods that are applied to the systems under experimental study. They are already well recognized for contributions to both exact and approximate theories of quantum dynamics, and a wide range of advances in electronic structure theory that have become broadly used in many other groups.
Schematic of fast radical beam instrument.
Key current activity in electronic structure theory is the introduction of combinatorial design strategies for density functionals, the most widely used quantum chemistry methods. This work is leading to new functionals which require fewer parameters than existing ones, and yet have greater predictive power.
In chemical dynamics, activity centers on the development of tractable semi-classical dynamics approaches that can address non-adiabatic processes. The focus is on turning semi-classical theory into a practical way of adding quantum effects to classical molecular dynamics simulations of large, complex molecular systems. Our new methods, as well as existing approaches, are employed to study prototype radical reactions.