High-resolution ro-vibrational and rotational spectroscopy of the open-shell, linear CCH${}^{+}$ ion (${}^3\Pi$)

Abstract

In this work, we report on the high-resolution infrared spectrum of CCH${}^{+}$ (${}^3\Pi$) recorded in the range $3066-3184$~cm${}^{-1}$ by means of leak-out spectroscopy. This spectral range covers the fundamental of the CH stretching mode and a highly excited bending vibrational mode. Based on this data (385 ro-vibrational lines), accurate spectroscopic descriptions of the ground and the two vibrationally excited states of CCH${}^{+}$ were obtained. Besides the band origins, spin-orbit coupling constants, rotational constants, centrifugal distortion constants and $\Lambda$-doubling constants for the ground and excited vibrational states have been derived. This effective Hamiltonian analysis allowed a search for pure rotational lines of CCH${}^{+}$ in its electronic and vibrational ground state using a two-color millimeterwave - infrared scheme. We observed all rotational transitions from $J^{\prime \prime }=2$ up to $J^{\prime \prime }=6$ within the $\Omega =2$ lowest energy fine structure component with resolved hyperfine splittings. This data has already guided the first detection of CCH${}^{+}$ in space toward the Orion Bar photo-dissociation region, and has the potential to support further astronomical searches for CCH${}^{+}$ either through radio or infrared spectroscopy, for example with the James Webb Space Telescope.

34 pages, 5 figures, supplementary information available on the journal webpage

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Cited by in corpus (1)

• Experimental proof of strong $\Pi$-$\Sigma$ mixing in the Renner-Teller and Pseudo-Jahn-Teller affected CCH${}^{+}$ (${}^3\Pi$) ion