In this project supported by the Chemical Structure, Dynamics and Mechanisms Program of the Division of Chemistry, Professor James Farrar of the University of Rochester and his research group will explore the collisions of free radicals and atomic or molecular ions, employing the velocity map imaging (VMI) method for product detection, using the instrument developed during the initial grant period. By employing a pulsed supersonic source of free radicals such as CH3 and C3H5, and an electron impact or discharge source of low energy cations such as N2+, N+, C+, O2+, and O+, and anions such as H-, O-, O2-, and OH-, the VMI detection method will produce differential cross sections in kinetic energy and angle. Of particular interest are the bond formation reactions that yield C-C, C-O, C-N, N-O, and H-H bonds. For anionic reactions, free electrons produced by associative detachment will be detected. The experiments will produce information on the dynamics of reactions of low energy ions with free radicals, an area of ion chemistry with few extant examples in the literature. The work will address the serious deficiencies of models for electrical discharges and the chemistry of planetary atmospheres that do not include ion-radical reactions. A study of the H- + H associative detachment reaction will have important implications for astrophysics.
In addition to characterizing the dynamics of these chemical systems, this research will provide a deeper understanding of reactivity patterns and a molecular understanding of the chemistry that takes place in reactive ion etching, and in atmospheric and extraterrestrial chemistry. The instrumental technique development may have impacts in various subdisciplines of chemistry, including mass spectrometry and ion imaging. The students and post-doctoral associates involved in this research will contribute to the national scientific and economic infrastructure through the development of new measurement technologies, new high value-added products, and the further training of scientific personnel.
