INFRARED RESONANCE ENHANCED PHOTODISSOCIATION SPECTROSCOPY OF $Ni^{+}(CO_{2})_{n}, Ni^{+}(CO_{2})_{n}Ar$, AND $Ni^{+}(O_{2})(CO_{2})_{n}$ CLUSTERS
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Date
2003
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Publisher
Ohio State University
Abstract
$Ni^{+}(CO_{2})_{n}$, and $Ni^{+}(CO_{2})_{n}Ar$ ion-molecule complexes are produced by laser vaporization in a pulsed nozzle source and studied with mass-selected infrared resonance-enhanced photodissociation spectroscopy (IR-REPD). Photofragment yield is measured as a function of energy in the region of the asymmetric stretch vibration of $CO_{2} (2349 cm^{-1})$. Fragmentation of $Ni^{+}(CO_{2})_{n}$ complexes proceeds by the loss of intact $CO_{2}$ units. The mixed clusters fragment by loss of Ar, permitting higher photofragment yields and sharper spectra than those provided by the corresponding pure $Ni^{+}(CO_{2})_{n}$ complexes. Spectra for the $n \leq 4$ complexes depict asymmetric stretches to the blue of free $CO_{2}$ while solvation effects are observed in the larger complexes. An additional blue-shifted band is observed in complexes with $ n\geq 6$, indicating that the $Ni^{+}$ ion participates in a cluster-assisted chemical reaction producing a nickel oxide. This inference is supported by the results of experiments on $Ni^{+}(O_{2})(CO_{2})_{n}$ complexes, where a blue-shifted band is also observed.
Description
Author Institution: Department of Chemistry, University of Georgia