Knowledge Bank

$Ni+(CO2)n$, and $Ni+(CO2)nAr$ 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 $CO2(2349cm-1)$. Fragmentation of $Ni+(CO2)n$ complexes proceeds by the loss of intact $CO2$ units. The mixed clusters fragment by loss of Ar, permitting higher photofragment yields and sharper spectra than those provided by the corresponding pure $Ni+(CO2)n$ complexes. Spectra for the $n\le 4$ complexes depict asymmetric stretches to the blue of free $CO2$ 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 $Ni+(O2)(CO2)n$ complexes, where a blue-shifted band is also observed.