title: Higher excited electronic transitions of polyacetylene cations HC2nH+ n = 2-7 in neon matrixes.
abstract: The polyacetylene HC2nH+ n = 2-7 cations were produced from a mixture of diacetylene with helium in a hot cathode-discharge source. After a mass-selective deposition, their absorption spectra were studied in 6 K neon matrixes. Besides the known A2Pi <-- X2Pi system, several new transitions to higher excited 2Pi electronic states of these cations have been observed. In the case of HC4H+ and HC6H+, only one new weak absorption system has been detected with the onset at 336.1 and 417.2 nm, respectively. These C2Pi <-- X2Pi transitions form a series that extends to HC10H+. Two further electronic transitions are observed for HC8H+ through to HC14H+; a weaker B2Piu <-- X2Pig and a strong E2Piu <-- X2Pig in the UV. The integrated intensity of the UV system of the polyacetylene cations exceeds that of the A2Pi <-- X2Pi transition by an order of magnitude.
authors.affiliation: Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland.
authors.forename: Jan
authors.initials: J
authors.lastname: Fulara
authors.forename: Michel
authors.initials: M
authors.lastname: Grutter
authors.forename: John P
authors.initials: JP
authors.lastname: Maier