Abstract
view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Interstellar Molecule Formation. Stecher, Theodore P. ; Williams, David A. Abstract The formation of interstellar molecules is shown to be the result of chemical reactions on the surfaces of the interstellar grains. Previous investigation has shown that the formation of molecules by physical adsorption of the molecular constituents on the grain with a subsequent three- body reaction is inoperative on ice. It is shown here that it is also of no consequence for graphite and Platt particles. The formation process described involves exchange reactions between incident atoms and atoms chemically bound into the grain. The theory of chemical exchange is shown to apply to all types of grain and is then illustrated with graphite flakes. Production rates are given for H2, CH, OH, NH, CN, CO, and N2 as functions of temperature and pressure. Destruction of the molecules is due to photodissociation by starlight and other chemical exchange reactions. The varying conditions in the interstellar medium are considered. No molecules are formed when the gas is quiescent. With the higher temperatures of doud~loud collisions H2 is formed, and it is shown that a minimum of 43 of all interstellar hydrogen atoms are in H2 molecules. CH +CH+, OH, and CN are produced by chemical exchange in the observed amounts when graphite grains are driven at supersonic speeds through the gas by radiation pressure. The process predicts the formation of H2, CO, NH, N2 from graphite flakes and possibly Platt particles. Publication: The Astronomical Journal Pub Date: 1966 DOI: 10.1086/110169 Bibcode: 1966AJ.....71T.399S full text sources ADS |
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