Argon cluster-mediated isolation and vibrational spectra of peroxy and nominally D3h isomers of CO3− and NO3−

Abstract

Vibrational predissociation spectra are reported for two isomeric forms of the gas-phase ions, CO(3)(-) and NO(3)(-). The peroxy forms, (OOCO(-) and OONO(-)) were isolated using an Ar-mediated synthetic scheme involving exchange of CO and NO for the more weakly bound Ar ligands in O(2)(-)Ar(m) clusters, while the forms based on a central heteroatom (CO(3)(-) and NO(3)(-)) were generated by electron impact on CO(2) and HNO(3) vapor. The simple two-band spectrum of OOCO(-) indicates that it is best described as the O(2)(-) x CO ion-molecule complex, whereas the covalently bound CO(3)(-) form yields a much more complicated vibrational spectrum with bands extending out to 4000 cm(-1). In contrast, the NO(3)(-) ion yields a simple spectrum with only one transition as expected for the antisymmetric NO stretching fundamental of a species with D(3h) structure. The spectrum of the peroxynitrite isomer, OONO(-), displays intermediate complexity that can be largely understood in the context of fundamentals associated with its cis and trans structures previously characterized in an Ar matrix.