Cobalt carbene ion: reactions of Co+ with C2H4, cyclo-C3H6 and cyclo-C2H4O

Journal ArticleAn ion beam apparatus is employed to study the formation of the cobalt carbene ion, CoCH2+. This ion is produced in the endothermic reaction of cobalt ions with ethene and cyclopropane and in an exothermic reaction with ethylene oxide. A model is proposed to account for the dependence of experimental cross sections on relative kinetic energy for the endothermic reactions. Using this model to interpret the experimental results, a bond dissociation energy D°(Co+-CH2 ) = 3.7+0.3 eV is derived

Effect of kinetic and electronic energy on the reactions of Mn+ with H2, HD and D2

Journal ArticleReactions of several electronic states of Mn+ with H2, HD, and D2 have been examined using guided ion beam mass spectroscopy. The excitation function for the ground state of Mn+ ( 75) has two regions: one of very low reactivity at threshold and another more efficient pathway at higher energies. In contrast, the 5S and 5D states react efficiently at their thermodynamic thresholds. In reaction with HD, the 5S and 5D states produce s 3 times as much MnH+ as MnD+ in the threshold region

Relative and absolute bond dissociation energies of sodium cation-alcohol complexes determined using competitive collision-induced dissociation experiments

ManuscriptAbsolute (R1OH)Na+-(R2OH) and relative Na+-(ROH) bond dissociation energies are determined experimentally by competitive collision-induced dissociation of (R1OH)Na+(R2OH) complexes with xenon in a guided ion beam mass spectrometer. The alcohols examined include ethanol, 1-propanol, 2-propanol, n-butanol, iso-butanol, sec-butanol, and tert-butanol, which cover a range in Na+ affinities of only 11 kJ/mol. Dissociation cross sections for formation of Na+(R1OH) + R2OH and Na+(R2OH) + R1OH are simultaneously analyzed with a model that uses statistical theory to predict the energy dependent branching ratio. The cross section thresholds thus determined are interpreted to yield the 0 K (R1OH)Na+-(R2OH) bond dissociation energies and the relative 0K Na+-(ROH) binding affinities. The relative binding affinities are converted to absolute 0 K Na+-(ROH) binding energies by using the absolute bond energy for Na+-C2H5OH determined previously in our laboratory as an anchor value. Comparisons are made to previous experimental and theoretical Na+-(ROH) thermochemistry from several sources. The absolute (R1OH)Na+-(R2OH) bond dissociation energies were also calculated using quantum chemical theory at the MP2(full)/6-311+G(2d,2p)//MP2(full)/6-31G(d) level (corrected for zero-point energies and basis set superposition errors) and are generally in good agreement with the experimentally determined values

Effect of kinetic and electronic energy on the reactions of Cr+ with H2, HD, and D2

Journal ArticleThe reactions of atomic chromium ions with H2 , HD, and D2 are examined using guided ion beam tandem mass spectrometry. The ground electronic state (6S) is found to react inefficiently. The thresholds of these data are analyzed to yield a 0 K bond dissociation energy for CrH+ of 1.37 ± 0.09 eV (31.6 ± 2.0 kcal/mol). In the reaction of Cr+ (6S) with HD, formation of the metal deuteride ion is strongly favored over that of the metal hydride ion in the threshold region but not at higher energies. These results indicate that Cr+ (6S) reacts largely via an impulsive mechanism. No evidence for reaction of Cr+ (6Z>), the first excited state, is found but higher lying excited states, 4D and 4G (produced by electron impact), are found to react at their thermodynamic threshold. In reaction with HD, these states produce CrH+ preferentially by a factor of 2-4 over CrD+ . The differences in reactivity among these states can be explained by using simple molecular orbital concepts which have been developed for other atomic transition metal ions

Translational energy dependence of O+(4S) + N2 → NO+ + N from thermal energies to 30 eV c.m.

Journal ArticleGuided ion beam mass spectrometry is used to examine the kinetic energy dependence of the reaction of ground state atomic oxygen ion with molecular nitrogen. An 0 + (4S) source which produces less than 0.06% excited states is described. Cross sections for the NO+ + N product channel decrease with increasing energy below 0.25 eV but increase with energy at higher energies

Reaction of Cr + , Mn + , Fe + , Co + , and Ni + with O2 and N2O. Examination of the translational energy dependence of the cross sections of endothermic reactions

Reactions of Cr + , Mn + , Fe + , Co + , and Ni + with O2 and N2O to yield metal oxide ions are examined using an ion beam apparatus. Reaction cross sections sigma as a function of ion translational energy E are reported. With one exception, Fe + +N2O, the cross sections exhibit an energy threshold Eo. Several models are used to interpret the excitation functions for the O2 reactions and it is concluded that the classical line-of-centers form sigma alpha (1–Eo/E) is most useful. Bond energies derived in this manner are D°(CrO + ) = 3.45±0.1 eV, D°(MnO + ) = 2.48±0.1 eV, D°(FeO + ) = 3.01±0.1 eV, D°(CoO + ) = 2.76±0.1 eV, and D°(NiO + ) = 1.95±0.1 eV. Since these bond energies are all greater than D°(N2–O) = 1.7 eV, the observation of energy thresholds for the reactions with N2O are surprising. These results are explained in terms of a qualitative view of the electronic potential energy surfaces involved

A Cloudy/Xspec Interface

We discuss new functionality of the spectral simulation code CLOUDY which allows the user to calculate grids with one or more initial parameters varied and formats the predicted spectra in the standard FITS format. These files can then be imported into the x-ray spectral analysis software XSPEC and used as theoretical models for observations. We present and verify a test case. Finally, we consider a few observations and discuss our results.Comment: 13 pages, 1 table, 4 figures, accepted for publication in PAS

New Indicators for AGN Power: The Correlation Between [O IV] lambda 25.89 micron and Hard X-ray Luminosity for Nearby Seyfert Galaxies

We have studied the relationship between the [O IV] lambda 25.89 micron emission line luminosities, obtained from Spitzer spectra, the X-ray continua in the 2-10 keV band, primarily from ASCA, and the 14-195 keV band obtained with the SWIFT/Burst Alert Telescope (BAT), for a sample of nearby (z < 0.08) Seyfert galaxies. For comparison, we have examined the relationship between the [O III] 5007, the 2-10 keV and the 14-195 keV luminosities for the same set of objects. We find that both the [O IV] and [O III] luminosities are well-correlated with the BAT luminosities. On the other hand, the [O III] luminosities are better-correlated with 2-10 keV luminosities than are those of [O IV]. When comparing [O IV] and [O III] luminosities for the different types of galaxies, we find that the Seyfert 2's have significantly lower [O III] to [O IV] ratios than the Seyfert 1's. We suggest that this is due to more reddening of the narrow line region (NLR) of the Seyfert 2's. Assuming Galactic dust to gas ratios, the average amount of extra reddening corresponds to a hydrogen column density of ~ few times 10^21 cm^-2, which is a small fraction of the X-ray absorbing columns in the Seyfert 2's. The combined effects of reddening and the X-ray absorption are the probable reason why the [O III] versus 2-10 keV correlation is better than the [O IV] versus 2-10 keV, since the [O IV] emission line is much less affected by extinction. Overall, we find the [O IV] to be an accurate and truly isotropic indicator of the power of the AGN. This suggests that it can be useful in deconvolving the contribution of the AGN and starburst to the spectrum of Compton-thick and/or X-ray weak sources.Comment: Accepted for publication in the Astrophysical Journal. 31 pages, 6 figures, 4 table

Cobalt carbene ion: Reactions of Co+ with C2H4, cyclo-C3H6, and cyclo-C2H4O

An ion beam apparatus is employed to study the formation of the cobalt carbene ion, CoCH + 2. This ion is produced in the endothermic reaction of cobalt ions with ethene and cyclopropane and in an exothermic reaction with ethylene oxide. A model is proposed to account for the dependence of experimental cross sections on relative kinetic energy for the endothermic reactions. Using this model to interpret the experimental results, a bond dissociation energy D°(Co+–CH2)=3.7±0.3 eV is derived