The rotational spectrum of ¹²C₂HD in the ground and excited bending states: an improved ro-vibrational global analysis

¹ Dipartimento di Chimica “Giacomo Ciamician”Università di Bologna, via F. Selmi 2, 40126 Bologna, Italy
e-mail: claudio.degliesposti@unibo.it; luca.dore@unibo.it
² Dipartimento di Chimica Industriale “Toso Montanari”, Università di Bologna, viale del Risorgimento 4, 40136 Bologna, Italy
e-mail: luciano.fusina@unibo.it; filippo.tamassia@unibo.it

Received: 26 July 2013
Accepted: 11 October 2013

Abstract

Rotational transitions of ¹²C₂HD were recorded in the range 100–700 GHz for the vibrational ground state and for the bending states v₄ = 1 (Π), v₅ = 1 (Π), v₄ = 2 (Σ⁺ and Δ), v₅ = 2 (Σ⁺ and Δ), v₄ = v₅ = 1 (Σ⁻, Σ⁺ and Δ), v₄ = 3 (Π and Φ) and v₅ = 3 (Π and Φ). The transition frequencies measured in this work were fitted together with all the infrared ro-vibrational transitions involving the same bending states available in the literature. The global fit allowed a very accurate determination of the vibrational, rotational, and ℓ-type interaction parameters for the bending states up to v₄ + v₅ = 3 of this molecule. The results reported in this paper provide a set of information very useful for undertaking astronomical searches in both the mm−wave and the infrared spectral regions. The parameters from the global fit can be used to calculate accurate rest frequencies for rotational transitions in the ground state or in excited vibrational states involving the bending modes. Pure rotational transition frequencies up to 1 THz are listed.