Beauchamp, J. L. (1976) Ion cyclotron resonance studies of endothermic reactions of UF6- generated by surface ionization. Journal of Chemical Physics, 64 (3). pp. 929-935. ISSN 0021-9606 http://resolver.caltech.edu/CaltechAUTHORS:BEAjcp76b
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Ion cyclotron resonance spectroscopy is used to investigate endothermic reactions of UF6-. At temperatures below those required for electron emission, UF6- is formed by negative surface ionization on a directly heated rhenium filament. The reactant ion is accelerated to a known energy and traverses the source region of the ICR cell in the direction of the magnetic field. Slow products from reactive and nonreactive encounters are confined in the trapping well and detected in the usual manner. The formation of UF7-, UF6-, UF5-, and UF3- from the reaction of UF6- with UF6 is studied over the energy range 0–40 eV in the center of mass. The cross section for UF7- formation exhibits a threshold at a relative kinetic energy of 2.7 eV. Reaction of UF6- with BF3 leads to formation of BF4- with a threshold of 1.6 eV in the center of mass. From these thresholds, E.A.(UF6) =4.9±0.5 eV is deduced and the bond dissociation energies D (UF5–F−) =108±6 kcal/mole and D (UF6–F−) =46±10 kcal/mole are calculated. The endothermic reaction of UF6- with SF6 to produce SF6- is also investigated, the cross section for the process exhibiting a gradual onset at ~7.5 eV, considerably above the thermodynamic threshold. The experimental techniques for using ion cyclotron resonance spectroscopy to study endothermic reactions of positive and negative ions formed by surface ionization are considered in detail.
|Additional Information:||Copyright © 1976 American Institute of Physics. Received 15 September 1975. This work was supported in part by the Energy Research and Development Administration under Grant No. AT(04-3)767-8 and the Ford Motor Company Fund for Energy Research administered by the California Institute of Technology. The instrument used in these studies was funded by the National Science Foundation under Grant No. NSF-GP-18383. Contribution No. 5164 from the Arthur Amos Noyes Laboratory of Chemical Physics.|
|Subject Keywords:||URANIUM HEXAFLUORIDE, IONIZATION, CYCLOTRON RESONANCE, AFFINITY, HEAT OF DISSOCIATION|
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|Deposited On:||17 Jan 2009 07:55|
|Last Modified:||26 Dec 2012 10:44|
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