Paul D. Cooper

Chemistry in Water Ices: From Fundamentals to Planetary Applications

Laboratory studies pertinent to the chemistry of ices with and without additional ingredients such as organics is critical to our understanding of how solar system icy bodies from comets and Kuiper Belt Objects far away in the outer solar system to the ices on Earth, much closer to the sun. This chapter reviews our present day understanding of the fundamental processes that occur in water-rich ices, containing organic impurities. In particular, the role of radiation – photons, electrons, and ions on the chemical evolution of solar system ices, including the newly discovered photoionization in ices, are reviewed.

Formation of methanol from methane and water in an electrical discharge

Matrix isolation FTIR experiments have shown that methanol is a major product when argon gas doped with water and methane is exposed to an electrical discharge and condensed to a solid matrix at 11 K. Experiments with (2)H, (17)O and (18)O-labeled isotopologues show the mechanism for the methanol production is likely to be insertion of an excited oxygen atom in the (1)D state into a C-H bond of a methane molecule. In light of these experiments, the possibility of oxygen atom insertion into methane should be considered as a possible mechanism for the production of methanol in interstellar ices.

Altitude profile of the OH radical complex with water in Earth’s atmosphere: a quantum mechanical approach

The hydroxyl radical (OH) is important in both tropospheric and stratospheric chemical processes that occur in Earth’s atmosphere. The OH radical can also strongly hydrogen-bond to form complexes with other atmospheric constituents, like water molecules. Consequently, there is potential for altered reaction dynamics/kinetics as a result of this complexation. Without direct measurements of the abundances of such complexes in Earth’s atmosphere, we have adopted a theoretical approach to determine such abundances. Electronic structures, enthalpies and free Gibbs energies of formation of OH, H2O and H2O-HO were calculated at CCSD(T) and QCISD(T) levels of theory with either 6–311++G(2d,2p) or aug-cc-pVTZ basis. Statistical thermodynamic concepts were then used to assess the abundance of the complex as function of altitude.