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Probing the pyrolysis of methyl formate in the dilute gas phase by synchrotron radiation and theory
Authors:Bethany Lowe  Alejandro L Cardona  Juana Salas  Andras Bodi  Maxi A Burgos Paci  Paul M Mayer
Institution:1. Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, Canada;2. INFIQC-CONICET, Departamento Fisicoquímica, Universidad Nacional de Córdoba, Córdoba, Argentina;3. Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute, Villigen, Switzerland
Abstract:The thermal dissociation of the atmospheric constituent methyl formate was probed by coupling pyrolysis with imaging photoelectron photoion coincidence spectroscopy (iPEPICO) using synchrotron VUV radiation at the Swiss Light Source (SLS). iPEPICO allows threshold photoelectron spectra to be obtained for pyrolysis products, distinguishing isomers and separating ionic and neutral dissociation pathways. In this work, the pyrolysis products of dilute methyl formate, CH3OC(O)H, were elucidated to be CH3OH + CO, 2 CH2O and CH4 + CO2 as in part distinct from the dissociation of the radical cation (CH3OH+? + CO and CH2OH+ + HCO). Density functional theory, CCSD(T), and CBS-QB3 calculations were used to describe the experimentally observed reaction mechanisms, and the thermal decomposition kinetics and the competition between the reaction channels are addressed in a statistical model. One result of the theoretical model is that CH2O formation was predicted to come directly from methyl formate at temperatures below 1200 K, while above 1800 K, it is formed primarily from the thermal decomposition of methanol.
Keywords:computational chemistry  imaging photoelectron photoion coincidence spectroscopy  kinetic modeling  methyl formate  photoelectron spectroscopy  pyrolysis  reaction mechanisms
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