Infrared spectroscopic and theoretical study of the HC2n+1O+ (n = 2–5) cations

摘要

The carbon chain cations, HC2n+1O⁺ (n = 2–5), are produced via pulsed laser vaporization of a graphite target in supersonic expansions containing carbon monoxide and hydrogen. The infrared spectra are measured via mass-selected infrared photodissociation spectroscopy of the CO “tagged” [HC2n+1O·CO]⁺ cation complexes in the 1600-3500 cm⁻¹ region. The geometries and electronic ground states of these cation complexes are determined by their infrared spectra compared to the predications of theoretical calculations. All of the HC2n+1O⁺ (n = 2–5) core cations are characterized to be linear carbon chain derivatives terminated by hydrogen and oxygen, which have the closed-shell singlet ground states with polyyne-like carbon chain structures.