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Thermochemistry and Reactivity of Metals Engaged in Chemiionization

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Technical Report,01 Sep 2014,30 Sep 2015

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University of Utah Salt Lake City United States

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The exothermicity of the chemi-ionization reaction Sm O - SmO e has been re evaluated. Guided ion beam tandem mass spectrometry GIBMS has been used to determine a value for the bond dissociation energy of SmO of 5.73 - 0.07 eV, as determined by the observed reactivity of Sm and SmO with several species. Combined with the established Sm ionization energy, this value indicates an exothermicity of the chemi-ionization reaction of 0.08 - 0.07 eV, 0.2 eV smaller than previous literature determinations. This value agrees well with 0.14 - 0.17eV, independently determined from a new measurement of the ionization energy of SmO using resonantly enhanced two-photon ionization REMPI and pulsed-field ionization zero kinetic energy PFI-ZEKE photoelectron spectroscopy, 5.7427 - 0.0006 eV, combined with literature bond energies of SmO. The evaluated thermochemistry also suggests that D0SmO 5.83 - 0.07 eV, consistent with but more precise than literature values. Implications of these results for interpretation of chemical release experiments in the thermosphere were evaluated.

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