Small Molecule Photodissociation in Solid Parahydrogen

University Of Wyoming, Laramie WY

Investigators

Abstract

David Anderson of the University of Wyoming is supported by the Experimental Physical Chemistry Program for research to verify experimentally to what extent chemistry can be halted in cryogenic crystals of molecular hydrogen. Chemical impurities added to hydrogen crystals at low concentrations will be photochemically transformed in situ into reactive species such as radicals. Once the reactive species are shown to be trapped in solid hydrogen by infrared spectroscopy, laser excitation will be used to initiate chemical reactions under highly controlled conditions in order to explore low temperature condensed phase reaction dynamics at a molecular level of detail. Two important radical target species are the imidogen radical (NH) and the hydroxyl radical (OH), whose reactions with molecular hydrogen in the cryogenic hydrogen matrix will be studied. Other possible radicals for hydrogen matrix study include NO, methyl radical, and CN. Project outcomes are expected to provide chemical and photophysical information useful for predicting outcomes of laser initiated chemical reactions in novel low temperature condensed hydrogen from first principles. Frozen molecular hydrogen is an unusual condensed material, since at the low temperatures at which it solidifies, the hydrogen crystal properties are dominated by quantum mechanical behavior. Anderson's studies of reactions in solid hydrogen will test the fundamental concepts involved in low temperature condensed phase chemistry, provide insights into chemistry (or lack of it) occurring in and on the surface of planets such as Jupiter, and potentially allow for new ways of controlling chemical reaction pathways.