Mark Smith of the University of Arizona is supported by the Experimental Physical Chemistry Program and Galactic Astronomy Program to study ion-molecule reaction rate coefficients of importance to both fundamental reaction mechanisms and naturally complex chemical environments over a wide temperature range (4-800K). A next generation variable temperature multipole trap mass spectrometer employing neutral molecular beams will be constructed, allowing for a) multiple reaction probes of trapped ions including the capability to interact trapped ions with a low velocity, dense molecular beams of condensable species and to chemically probe reaction products, b) in situ synthesis of complex molecular ions using pulsed reagent gas/buffer gas collisional cooling for subsequent beam species rate measurements, and c) future studies using other techniques such as state-selected laser pumping of ions and velocity selection of neutral beams. Well-developed chemical probing and ion packet control will allow reaction and product studies under unambiguous collision conditions. Specific projects include studies of gas phase hydrogenation of hydrocarbon cations at low temperatures, studies of the HOC cation relevant to the interstellar medium, and exploration of the structure of radiative association products. The results will allow for precise determination of reactivity and mechanism under a wide range of energy conditions, and outcomes are expected lead to new insights into reaction mechanisms, chemical isomerization, isotopic fractionation, and energy transfer.
This research is expected to improve the foundation of low temperature reaction dynamics as well as astrochemical laboratory studies, enhancing international collaboration. The inherently interdisciplinary program will help to develop some of the next generation of scientists to move into this emerging area, and benefit the growth of astrochemistry at the University of Arizona.
