Chemistry in Extreme Environments

1
Chemistry in Extreme Environments  Chris Bennett,
Xibin Gu, Brant Jones, Pavlo Maksyutenko,
Fangtong Zhang, Ralf I. Kaiser Department of
Chemistry, University of Hawaii at Manoa,
Honolulu, HI 96822 UH NASA Astrobiology
Institute, Institute for Astronomy, University of
Hawaii at Manoa, HI 96822
Topic II We have completed our research program
on the formation mechanisms and stability of
higher carbon oxides COn (n3-6). These molecules
have long been known as important molecules in
atmospheric (Earth, Mars) 18O isotope enrichment
processes and in solid state chemical reactions.
We have synthesized and characterized a total of
five higher carbon oxides via low temperature
spectroscopy at 10 K by irradiating carbon
dioxide ices with energetic electrons. These are
CO3 C2v, CO3 D3h, CO4 C2v D2d, CO5 C2,
and CO6 Cs. All assignments have been confirmed
in 12C18O2, 13C16O2, and 13C18O2 systems. The
time-dependent concentration profiles of the
carbon oxides suggest that the CO3 molecules are
initially formed by an addition of a suprathermal
oxygen atom to the carbon-oxygen double bond and
to the carbon atom to form CO3 C2v and CO3
D3h, respectively. As the irradiation time
increases, the ring structure is expanded
successively to form CO4 C2v, CO5 C2, and CO6
Cs R.I. Kaiser, A.M. Mebel, Frontiers Article.
Chem. Phys. Lett. 465, 1-9 (2008).
 Topic I We are expanding our studies of
atomic boron reactions and aim to elucidate the
energetics and dynamics of elementary reactions
of ground state boron atoms (B(2Pj)) with simple
nitrogen- and oxygen-bearing molecules. These
studies focus on the key systems ammonia (NH3)
and hydrogen cyanide (HCN) as well as water
(H2O), oxygen (O2), and carbon dioxide (CO2). The
closed shell molecules serve as prototype
reaction partners to access the HxBCyN
(x0,1,2,3 y0,1) and HxBCyOz (x0,1,2 y0,1
z1,2) potential energy surfaces which are
important in the fields of basic physical
chemistry (reaction dynamics), combustion
chemistry, material sciences, chemical propulsion
systems, physical organic chemistry, and chemical
vapor deposition processes (boron-nitride films,
ternary BCN compounds). The experiments are
pooled together with electronic structure
calculations (Mebel, Florida International
University Newhouse, Maui High Performance
Computing Center) to verify the elucidated
reaction mechanisms theoretically this will
ultimately bridge the understanding of reactive
scattering processes involving small
boron-bearing systems via quantum chemical
methods and experiments.
 Topic III We have started a new research
component to investigate the effects of ionizing
radiation with (surface coated) polymers (Kapton,
Teflon, PE, PMMA). These experiments help to
untangle the stability of polymers together with
their coatings toward space weathering
originating from galactic cosmic ray particles
(GCRs), solar wind particles (mainly 1 keV H, 4
keV He, and 10 keV O), and mono energetic
UV/VUV photons up to 10.2 eV (Lyman Alpha).
Calculations utilizing the TRIM and CASINO codes
suggest that although Al2O3 coatings of a few nm
thick- ness protect polymers from hyperthermal
oxygen atoms, these coatings can be penetrated
easily by GCRs and solar wind particles.
Experiments are currently in progress to untangle
the chemical and physical effects of the
processing of these surface coated polymers with
charged particles and photons over a broad
temperature range from 10 K to 330 K.