Fundamental Interactions

Since its inception Argonne has been involved in long-term fundamental research that addresses problems in the chemical sciences that are related to the mission-oriented activities of the Department of Energy. Our programs in this area are directed to basic research in atomic, molecular and optical science; chemical physics; photochemistry; and physical chemistry. Our research seeks to understand chemical reactivity through studies of the interactions of atoms, molecules, and ions with photons and electrons; the making and breaking of chemical bonds in the gas phase; and energy transfer processes within and between molecules.

Ultimately, this research leads to the development of such advances as efficient combustion systems with reduced emissions of pollutants, new solar photoconversion processes, and improved development and application of novel x-ray light sources at current and planned DOE user facilities.

Atomic, Molecular, and Optical Physics

This program combines experiment and theory in developing a quantitative understanding of x-ray interactions with atoms and molecules from the weak-field limit to the strong-field regime. Research thrusts are in x-ray probes of optical strong-field processes, inner-shell processes with intense ultrafast x-rays, theory and the development of synchrotron-based 1 ps x-ray source at the Advanced Photon Source. Experimental results are used to challenge and calibrate some of the most detailed theoretical models in atomic physics.

Chemical Dynamics

This program merges theoretical and experimental work on the energetics, kinetics, and dynamics of chemical reactions in the gas phase with particular emphasis on combustion reactions. Shock tube, flow tube, and photo-ionization techniques provide fundamental measurements on the high- and low-temperature kinetics of radical-radical and radical-molecule reactions, on the thermochemistry of radicals, and on vibrational/rotational selected photodissociation of small molecules. A comparable theoretical effort maps out potential energy surfaces by electronic structure techniques; follows the dynamics and kinetics on surfaces with trajectories, wave packets, and statistical models; and couples multiple processes together in kinetics simulations. The synergism between comparable experimental and theoretical efforts is a hallmark of this effort.

Solar Conversion

Researchers are defining the basic principles in solar energy conversion that govern charge separation in molecules via the study of electron transfer reactions within natural and biomimetic photosynthetic structures. Work on the mechanism of charge separation in natural photosystems is being extended to construct novel artificial systems to mimic the natural process. The program approach features the resolution of structural dynamics linked to ET reactions by the application of a suite of advanced, multi-frequency, pulsed magnetic resonance, transient optical, and x-ray techniques to follow light-activated structural dynamics across multiple time (10^-13 s to 1 s) and length (1 Å to 500 Å) scales. The research develops a fundamental understanding of structure-function relationships in biological photosynthesis and establishes principles for the design of biomimetic systems for solar energy conversion.