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Accurate ro-vibrational rest frequencies of DC4H at infrared and millimetre wavelengths

F. Tamassia, L. Bizzocchi, C. Degli Esposti, L. Dore, M. Di Lauro, L. Fusina, M. Villa, E. Canč


Context. Diacetylene, C4H2, has been identified in several astronomical environments through its infrared spectrum. In contrast, monodeuterated diacetylene (DC4H) has not been detected in space so far owing to the low isotopic abundance of deuterated species but also to the rather poor laboratory spectroscopic characterisation of this molecule.

Aims. The aim of this work is to provide accurate spectroscopic parameters for DC4H to achieve reliable predictions for both its spectra at millimetre and infrared wavelengths.
Methods. We studied the rotational spectrum of DC4H in the range 85–615 GHz by millimetre-wave spectroscopy and the infrared spectrum below 1000   cm-1 by high-resolution, Fourier-transform spectroscopy. Several pure rotational transitions were recorded in the ground state and in excited vibrational bending states. The three fundamental bands v6, v7, and v8 have been identified and assigned in the infrared spectrum.
Results. The rotational transitions were analysed together with the infrared data in a global fit that produces very accurate ro-vibrational parameters. The observed frequencies and wavenumbers are reported to provide precise guidance for astronomical searches.

ISM: molecules – line: identification – molecular data – molecular processes – infrared: ISM

Astronomy and Astrophysics
Volume 549, Number of pages A38_1
2013 January

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Instituto de AstrofĆ­sica e CiĆŖncias do EspaƧo Universidade do Porto Faculdade de Ciências da Universidade de Lisboa FundaĆ§Ć£o para a CiĆŖncia e a Tecnologia
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