In this project in the Experimental Physical Chemistry Program of the Chemistry Division, Burrow (University of Nebraska) and Jordan (University of Pittsburgh) will continue joint experimental and theoretical studies of temporary anion formation in gas-phase substituted hydrocarbons. Experimental studies at both institutions will examine vibrational excitation and dissociative attachment (DA) reactions in which stable fragment anions are produced. Both total DA cross sections and vertical attachment energies (VAEs) for formation of temporary anions will be measured. A new instrument will be constructed to measure the angular dependence of fragment anions produced by DA. The effect of solvation on the energies and decay properties of temporary anions will be examined in methyl chloride (CH3Cl) co-expanded with solvents such as water. High-level electronic structure calculations will be carried out to predict how the vertical attachment energy is influenced by the solvation. A powerful means of visualizing molecular structure and chemical reactivity is provided by the concept of occupied and unoccupied electronic states, which are also known as orbitals. Photoelectron spectroscopy has long provided a means of studying occupied orbitals, but until recently the corresponding data for normally unoccupied orbitals has been scarce. This work aims at gathering such data, thereby helping to answer key chemical questions on structure and bonding in complex molecules. It also offers data crucial to models of electron transfer, which is the mechanism involved in a large variety of chemical processes, such as photosynthesis, light-induced desorption from surfaces, chemical carcinogenesis, and bioremediation.
