This grant from the Organic Dynamics Program supports the continuing work of Dr. Richard N. McDonald at Kansas State University. This work will provide an improved understanding of the chemical behavior in the gas phase of negatively charged ions formed from organic, inorganic, and organometallic molecules. The experiments that will be carried out by Dr. McDonald will afford information on two major photochemical reaction pathways for negatively charged ions: electron photodetachment (to produce a neutral species plus an electron), and ligand photodissociation (to produce two fragments, one neutral and one negatively charged). A tunable dye laser will be used to generate the excited-state ions, and the different negatively charged ions formed in the flowing afterglow will be monitored by mass spectroscopy. Dr. McDonald will utilize selected ion flow tube (SIFT) technology in tandem with the original technique to investigate the chemical reactivity of metal cluster ions.