Journal Article

PUBDB-2026-01996

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png High-Resolution Ro-Vibrational and Rotational Spectroscopy of the Open-Shell, Linear CCH$^+$ Ion $(^3Π)$

Steenbakkers, K. ; Silva, W. G. D. P. ; Asvany, O. ; Groenenboom, G. C. ; Jusko, P. ; Redlich, B.Extern*DESY* ; Brünken, S. (Corresponding author) ; Schlemmer, S. (Corresponding author)

2026
American Chemical Society Washington, DC

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Please use a persistent id in citations: doi:10.1021/acs.jpca.6c00521

Abstract: In this work, we report on the high-resolution infrared spectrum of CCH$^+$ ($^3$Π) 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 Λ-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″ = 2 up to J″ = 6 within the Ω = 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 photodissociation 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.

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Contributing Institute(s):

1. Bereichsleitung FS (FS)

Research Program(s):

1. 631 - Matter – Dynamics, Mechanisms and Control (POF4-631) (POF4-631)
2. DFG project G:(GEPRIS)172654239 - SPP 1573: Physics of the Interstellar Medium (172654239) (172654239)
3. SFB 1601 C04 - Ionenprozesse in verschiedenen kosmischen Epochen (C04) (525654802) (525654802)
4. SFB 1601 B08 - Infrarot und Fern-Infrarot Spektren molekularer Anionen (B08) (525633720) (525633720)
5. DFG project 504504934 - Optischer Parametrischer Oszillator (OPO) (504504934) (504504934)
6. DFG project G:(GEPRIS)450096019 - Mikrowellen - Infrarot Doppelresonanz Spektrometer (450096019) (450096019)

Experiment(s):

1. Measurement at external facility

Appears in the scientific report 2026

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Database coverage:
; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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