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Chemistry in Extreme Environments Chris Bennett, Xibin Gu, Brant Jones, Pavlo Maksyutenko, Fangtong Zhang, Ralf I. Kaiser Department of Chemistry, University.

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Presentation on theme: "Chemistry in Extreme Environments Chris Bennett, Xibin Gu, Brant Jones, Pavlo Maksyutenko, Fangtong Zhang, Ralf I. Kaiser Department of Chemistry, University."— Presentation transcript:

1 Chemistry in Extreme Environments Chris Bennett, Xibin Gu, Brant Jones, Pavlo Maksyutenko, Fangtong Zhang, Ralf I. Kaiser Department of Chemistry, University of Hawai’i at Manoa, Honolulu, HI 96822 UH NASA Astrobiology Institute, Institute for Astronomy, University of Hawaii at Manoa, HI 96822 Topic I 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( 2 P j )) with simple nitrogen- and oxygen-bearing molecules. These studies focus on the key systems ammonia (NH 3 ) and hydrogen cyanide (HCN) as well as water (H 2 O), oxygen (O 2 ), and carbon dioxide (CO 2 ). The closed shell molecules serve as prototype reaction partners to access the H x BC y N (x=0,1,2,3; y=0,1) and H x BC y O z (x=0,1,2; y=0,1; z=1,2) 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 II We have completed our research program on the formation mechanisms and stability of higher carbon oxides CO n (n=3-6). These molecules have long been known as important molecules in atmospheric (Earth, Mars) 18 O 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: CO 3 [C 2v ], CO 3 [D 3h ], CO 4 [C 2v ; D 2d ], CO 5 [C 2 ], and CO 6 [C s ]. All assignments have been confirmed in 12 C 18 O 2, 13 C 16 O 2, and 13 C 18 O 2 systems. The time-dependent concentration profiles of the carbon oxides suggest that the CO 3 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 CO 3 [C 2v ] and CO 3 [D 3h ], respectively. As the irradiation time increases, the ring structure is expanded successively to form CO 4 [C 2v ], CO 5 [C 2 ], and CO 6 [C s ] [R.I. Kaiser, A.M. Mebel, Frontiers Article. Chem. Phys. Lett. 465, 1-9 (2008)]. Topic III 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 Al 2 O 3 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.


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