FORMATION OF CARBON DIOXIDE, METHANOL, ETHANOL, AND FORMIC ACID ON AN ICY GRAIN ANALOG USING FAST OXYGEN ATOMS

Carbon dioxide (CO2), methanol (CH3OH), ethanol (CH3CH2OH), and formic acid (HCOOH) have been formed in collisions of a superthermal, 9 eV beam of O(3 P) atoms with CH4 molecules, with an over coat of CO molecules, adsorbed on a gold surface at 4.8 K. The products are detected using temperature programmed-desorption and quadrupole mass spectrometry. Identification of the species is carried out through use of the Metropolis random walk algorithm as constrained by the fractionation patterns of the detected species. Relative formation yields are reported and reaction sequences are given to account for possible formation routes.