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Ion-molecule reaction rate coefficients of
importance to our understanding of both
fundamental reaction mechanisms and naturally
complex chemical environments will be studied
over a wide temperature range (4-800 K). 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 to 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. Reactions
of cold cationic species relevant to the
interstellar medium will be investigated at
their natural temperatures. These studies will
equally provide insight into the effects of
nonequilibrium degrees of freedom in driving
endothermic processes and dynamical processes
requiring extremely long lived collision
complexes or proceeding through a limited set of
low lying reactant states.
The work
program will progressively make use of new
trapping technology to investigate variable
temperature reactions of selected hydrocarbon
ions with H2 followed by polar
molecule studies, the kinetics of reactions
leading to HCO+/HOC+
product isomers and a variety of key radiative
association processes of modest complexity.
Using chemical probing, product branching will
help clarify open questions regarding detailed
mechanisms in association reactions relevant for
synthesizing complex molecules in cold rarefied
environments. For example, in the well studied
reaction of CH3+ + HCN, which leads
to several isomers, new experiments will be
directed towards the so far undetected
protonated 2H-azirine product which is an
oxidation away from the interstellar synthesis
of glycine.
The activities
proposed will greatly improve the foundation of
low temperature reaction dynamics as well as
astrochemical laboratory studies, enhancing
international collaboration. The program will
help develop some of the next generation of
scientists to move into this emerging area. The
particular growth of astrochemistry at the
University of Arizona regarding the development
of new institutes, the formal bridging of
faculty across Chemistry, Astronomy and Biology
as well as the specific hiring activities in
astrochemistry will have a tremendous symbiotic
relationship to the proposed program.
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