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MO: Molekülphysik

MO 14: Spektroscopy II

MO 14.5: Talk

Friday, April 6, 2001, 16:45–17:00, H1058

Electronic spectra of polyacetylenic chains HC_2nH (n=8-13) in the gas phase — •Felix Güthe, Hongbin Ding, Thomas Pino, and John P. Maier — Institute for Physical Chemistry, University of Basel,Klingelbergstrasse 80, CH-4056 Basel, Switzerland

The intense ¹Σ _u⁺←— X¹Σ _g⁺ electronic transition of the polyacetylenic chains HC_2nH (n=8-13) has been recorded in the gas phase using resonant two color two photon ionisation spectroscopy. The gas phase frequencies lie ∼ 1300 cm⁻¹ to the blue of the values in neon matrix. These polyacetylenes appear to be linear in both the ground and the excited state and, as for the polyenes, spectral and theoretical evidence for large bond alternation in the ground state is found indicating localized π -orbitals on the C≡ C units. These species are the longest carbon chains observed spectroscopically in gas phase up to now.