The vibrational spectra of CO2+, (CO2)(2)(+), CO2-, and (CO2)(2)(-) trapped in solid neon

When a Ne:CO2 mixture is subjected to Penning ionization and/or photoioniza tion by neon atoms in their first excited states, between 16.6 and 16.85 eV , and the products are rapidly frozen at approximately 5 K, the infrared sp ectrum of the resulting deposit includes absorptions assigned to CO2+, (CO2 )(2)(+), CO2-, and (CO2)(2)(-). The lowest (mu (2)Sigma(u)(+)) Renner compo nent of the bending fundamental of CO2+ trapped in a neon matrix appears ne ar the gas-phase band center, but other Renner components are undetectable. Absorptions of a photolabile product correspond to the recently identified CO-stretching fundamentals of (CO2)(2)(+). Weak infrared absorptions at 12 53.8 and 714.2 cm(-1) are assigned to nu(1) and nu(2) of CO2-, respectively , and a moderately intense absorption at 2894.7 cm(-1) is assigned to the n u(1)+nu(3) combination band of that product. As in other recent argon- and neon-matrix studies, two weak infrared absorptions can be assigned to the t wo infrared-active OCO-stretching fundamentals of the D-2d structure of (CO 2)(2)(-). Detailed isotopic substitution studies support all of these assig nments. A weak absorption near the CO2 bending fundamental, for which isoto pic substitution data are incomplete, may be contributed either by a second fundamental of (CO2)(2)(-) (D-2d) with b(2) symmetry or by a weakly intera cting (CO2)(n).. CO2- complex. Such ion-molecule complexes contribute other absorptions near nu(3) of CO2 and of CO2-. (C) 1999 American Institute of Physics. [S0021-9606(99)00934-4].