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

Vibrational predissociation spectra are reported for two isomeric forms of the gas-phase ions, CO3- and NO3-. 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(-)center dot Ar-m clusters, while the forms based on a central heteroatom (CO3- and NO3-) were generated by electron impact on CO2 and HNO3 vapor. The simple two-band spectrum of OOCO- indicates that it is best described as the O-2(-)center dot CO ion-molecule complex, whereas the covalently bound CO3- form yields a much more complicated vibrational spectrum with bands extending out to 4000 cm(-1). In contrast, the NO3- 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. (C) 2008 American Institute of Physics.