VIBRATIONAL-SPECTRA OF CYCLIC C-6 IN SOLID ARGON

Vapors from solid and powdered carbon emitted from an oven cycled betw een 2000 and 3000 K were co-condensed with argon onto a CsI substrate maintained at 10 K. The cycling process produced a matrix ''sandwich'' with regions of high carbon density alternating with layers of argon. FTIR measurements including extensive C-13 isotopic data, supported b y ab initio calculations, allow the assignment of a band at 1694.7 cm( -1) to the nu(4)(e') fundamental of cyclic C-6. This represents the fi rst conclusive identification of a small cyclic neutral polycarbon. Ad ditionally, a vibration previously observed at 1710.3 cm(-1) has been confirmed as the nu(9)(sigma(u)) mode of linear C-g. (C) 1997 Publishe d by Elsevier Science B.V.