C-3(-) CARBON CLUSTER ANION - STRUCTURE AND ASYMMETRIC STRETCHING MODE FREQUENCY

Carbon cluster anions have been formed by a combination laser ablation /plasma generation method and then deposited in argon matrices and stu died via Fourier transform infrared spectroscopy. In this paper a full isotopic study of the C-3(-) anionic cluster is reported. All six iso topomeric bands of the nu(3) antisymmetric stretching mode at 1721.8 c m(-1) (all C-12 isotopomer) have been observed and used together with a normal coordinate calculation to deduce that C-3(-) in Ar matrices i s linear. This is in agreement with previous high-level ab initio calc ulations and with new density functional theory (DFT) and ab initio (M P2) results. Frequency shifts for all six C-3(-) isotopomers calculate d by DFT and MP2 approaches match the observed shifts very well. Final ly, evidence is presented that the C-3(-) anionic clusters are formed by electron capture and not by fragment aggregation.