title: Dissociative Photoionization of Diethyl Ether.
abstract: The dissociative photoionization of internal energy selected diethyl ether ions was investigated by imaging photoelectron photoion coincidence spectroscopy. In a large, 5 eV energy range Et2O(+) cations decay by two parallel and three sequential dissociative photoionization channels, which can be modeled well using statistical theory. The 0 K appearance energies of the CH3CHOCH2CH3(+) (H-loss, m/z = 73) and CH3CH2O═CH2(+) (methyl-loss, m/z = 59) fragment ions were determined to be 10.419 ± 0.015 and 10.484 ± 0.008 eV, respectively. The reemergence of the hydrogen-loss ion above 11 eV is attributed to transition-state (TS) switching, in which the second, outer TS is rate-determining at high internal energies. At 11.81 ± 0.05 eV, a secondary fragment of the CH3CHOCH2CH3(+) (m/z = 73) ion, protonated acetaldehyde, CH3CH═OH(+) (m/z = 45) appears. On the basis of the known thermochemical onset of this fragment, a reverse barrier of 325 meV was found. Two more sequential dissociation reactions were examined, namely, ethylene and formaldehyde losses from the methyl-loss daughter ion. The 0 K appearance energies of 11.85 ± 0.07 and 12.20 ± 0.08 eV, respectively, indicate no reverse barrier in these processes. The statistical model of the dissociative photoionization can also be used to predict the fractional ion abundances in threshold photoionization at large temperatures, which could be of use in, for example, combustion diagnostics.
authors.affiliation: Department of Chemistry, University of the Pacific , Stockton, California 95211, United States.
authors.forename: Krisztina
authors.initials: K
authors.lastname: Voronova
authors.affiliation: Department of Chemistry, University of the Pacific , Stockton, California 95211, United States.
authors.forename: Chrissa M
authors.initials: CM
authors.lastname: Mozaffari Easter
authors.affiliation: Department of Chemistry, University of the Pacific , Stockton, California 95211, United States.
authors.forename: Kyle J
authors.initials: KJ
authors.lastname: Covert
authors.affiliation: Molecular Dynamics Group, Paul Scherrer Institut , Villigen 5232, Switzerland.
authors.forename: Andras
authors.initials: A
authors.lastname: Bodi
authors.affiliation: Molecular Dynamics Group, Paul Scherrer Institut , Villigen 5232, Switzerland.
authors.forename: Patrick
authors.initials: P
authors.lastname: Hemberger
authors.affiliation: Department of Chemistry, University of the Pacific , Stockton, California 95211, United States.
authors.forename: Bálint
authors.initials: B
authors.lastname: Sztáray