The gas phase reaction of Th(+) with H(2)O to produce HThO(+) + H and ThO(+) + H(2) was investigated using density functional theory and coupled cluster methods. RRKM calculations of the branching ratio favor the H atomic elimination channel in disagreement with experiment. Ab initio classical trajectory calculations were carried out to obtain a better model of the molecular dynamics. The molec...

The puzzling mass-independent isotopic enrichment in ozone formation contrasts markedly with the more recently observed large unconventional mass-dependent ratios of the individual ozone formation rate constants in certain systems. An RRKM (Rice, Ramsperger, Kassel, Marcus)-based theory is used to treat both effects. Restrictions of symmetry on how energy is shared among the rotational/vibratio...

The collisionless photodissociation dynamics of isobutene (i-C(4)H(8)) at 193 nm via photofragment translational spectroscopy are reported. Two major photodissociation channels were identified: H + C(4)H(7) and CH(3) + CH(3)CCH(2). Translational energy distributions indicate that both channels result from statistical decay on the ground state surface. Although the CH(3) loss channel lies 13 kca...

We conducted the title reaction using a crossed molecular-beam apparatus, quantum-chemical calculations, and RRKM calculations. Synchrotron radiation from an undulator served to ionize selectively reaction products by advantage of negligibly small dissociative ionization. We observed two products with gross formula C(2)H(3)N and C(2)H(2)N associated with loss of one and two hydrogen atoms, resp...

The general approach to classical unimolecular reaction rates due to Thiele is revisited in light of recent advances in the phase space formulation of transition state theory for multidimensional systems. Key concepts, such as the phase space dividing surface separating reactants from products, the average gap time, and the volume of phase space associated with reactive trajectories, are both r...

The unimolecular dissociation and isomerization kinetics of the three methyl propanoate (MP) radicals, CH3CH2C(=O)OĊH2 (MP-m), CH3ĊHC(=O)OCH3 (MP-α), and ĊH2CH2C(=O)OCH3 (MP-β), are theoretically investigated using high-level ab initio methods and the Rice-Ramsperger-Kassel-Marcus (RRKM)/master equation (ME) theory. Stationary-point energies are obtained using the coupled cluster singles and do...

To provide an objective measure of the correlation between the internal energy content of ions generated by matrix-assisted laser desorption/ionization (MALDI) and the matrix properties, a series of well-characterized benzyl-substituted benzylpyridinium salts were used as thermometer molecules (TMs). To determine the internal energy variations of analyte ions, the survival yields of TM molecula...