Electronic and Infrared Spectra of HC2nO (n = 3–7) Chains

Abstract

Electronic and infrared spectra of HC2nO+ (n = 3–7) chains contained in a cryogenically cooled ion trap are measured using resonance-enhanced photodissociation spectroscopy. The HC2nO+ chains, which possess X̃3Σ– ground electronic states, are prepared through spin-forbidden association reactions between HC2n–1+ chains and CO molecules, both of which have X̃1Σ+ ground states. Infrared spectra of N2-tagged HC2nO+ (n = 4–7) chains measured over the 550–1820 cm–1 range exhibit weak bands associated with chain stretch and bend vibrational modes, with more intense C≡C and CO stretch bands predicted to occur in the 2200–2300 cm–1 region. Electronic spectra of bare HC2nO+ (n = 3–6) chains measured o..