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Title: The photodissociation of oxetane at 193 nm as the reverse of the Paterno-Buchi reaction

We investigated the photodissociation of oxetane (1,3-trimethylene oxide) at 193.3 nm in a molecular-beam apparatus using photofragment-translational spectroscopy and selective photoionization. We measured time-of-flight (TOF) spectra and angular anisotropy parameters {beta}(t) as a function of flight time of products at m/z=26-30 u utilizing photoionization energies from 9.8 to 14.8 eV. The TOF distributions of the products alter greatly with the employed photon energy, whereas their {beta}(t) distributions are insensitive to the photon energy. Dissociation to H{sub 2}CO+C{sub 2}H{sub 4} is the major channel in the title reaction. Three distinct dissociation paths with branching ratios 0.923:0.058:0.019 are responsible for the three features observed in the distribution of kinetic energy released in the channel H{sub 2}CO+C{sub 2}H{sub 4}. The observation of H{sub 2} and H atoms, {approx}1% in branching, indicates that products H{sub 2}CO and C{sub 2}H{sub 4} spontaneously decompose to only a small extent. Most HCO, C{sub 2}H{sub 3}, and C{sub 2}H{sub 2} ions originate from dissociative photoionization of products H{sub 2}CO and C{sub 2}H{sub 4}. Except atomic H and H{sub 2}, the photoproducts have large angular anisotropies, {beta}{>=}-0.8, which reflects rapid dissociation of oxetane following optical excitation at 193.3 nm. The mechanisms of dissociation of oxetane are addressed. Our resultsmore » confirm the quantum-chemical calculations of Palmer et al. and provide profound insight into the Paterno-Buchi reaction.« less
Authors:
 [1]
  1. National Synchrotron Radiation Research Center (NSRRC), 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan (China)
Publication Date:
OSTI Identifier:
21559814
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 131; Journal Issue: 22; Other Information: DOI: 10.1063/1.3270162; (c) 2009 American Institute of Physics
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ANISOTROPY; ATOMS; BRANCHING RATIO; CHEMISTRY; DISSOCIATION; DISTRIBUTION; ETHERS; ETHYLENE; EXCITATION; HETEROCYCLIC OXYGEN COMPOUNDS; HYDROGEN; KINETIC ENERGY; MOLECULAR BEAMS; PHOTOIONIZATION; PHOTOLYSIS; PHOTONS; REACTION KINETICS; SPECTROSCOPY; TIME-OF-FLIGHT METHOD; VINYL RADICALS ALKENES; ALKYL RADICALS; BEAMS; BOSONS; CHEMICAL REACTIONS; DECOMPOSITION; DIMENSIONLESS NUMBERS; ELEMENTARY PARTICLES; ELEMENTS; ENERGY; ENERGY-LEVEL TRANSITIONS; HETEROCYCLIC COMPOUNDS; HYDROCARBONS; IONIZATION; KINETICS; MASSLESS PARTICLES; NONMETALS; ORGANIC COMPOUNDS; ORGANIC OXYGEN COMPOUNDS; PHOTOCHEMICAL REACTIONS; RADICALS