New Technology for Exploring State-Dependent Reactivity in Radiative Association Reactions
Abstract: Recent advances in investigating radiative association (RA) reactions by quantum dynamics methods have revealed troubling discrepancies when compared with the reaction rates obtained using statistical methods, sometimes differing by up to four orders of magnitude. Notoriously difficult to measure in the laboratory, RA experiments are necessary to test the application of theoretical models to real systems. A new laboratory effort is being undertaken in the Chemistry Department at UMD to develop the tools necessary to experimentally measure rate constants for RA reactions at temperatures relevant to the interstellar medium (down to 10 K). The instrument combines a cryogenic buffer-gas beam with a cryogenic ion trap in order to investigate ion/molecule RA reactions as a function of temperature. In this talk, I will describe our progress toward the development of an instrument capable of directly measuring the temperature-dependent reactivities with the immediate goal of measuring the rate constants for a series of RA reactions between magnesium monocations (Mg+) and cyanopolyyne (HC2n+1N, n = 0–3) neutral molecules. These experiments will shed light on disagreement between theoretical RA studies, while also providing experimentally-measured rate constants for reactions that are relevant to astrochemistry.
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