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High-resolution infrared spectroscopy of diacetylene below 1000 cm-1

L. Bizzocchi, F. Tamassia, C. Degli Esposti, L. Fusina, E. Canč, L. Dore

Abstract
The infrared spectrum of diacetylene has been recorded at high resolution between 500 and 1000?cm-1 by Fourier transform spectroscopy. More than 1200 transitions were assigned to five bands: the ?8 fundamental, the ?7?+??9 combination, and the ?3?-??9 difference bands as well as the most intense ?8?+??9?-??9 and ?7?+?2?9?-??9 hot bands. The data were analysed together with the previously recorded millimetre-wave lines for the ?8?-??6 and ?8?+??9?-?(?6?+??9) difference bands. Rotational and vibrational l-type resonances, together with the cubic anharmonic interactions which couple the v 3?=?1 stretching state with the v 8?=?v 9?=?1 combination and v 7?=?2 overtone states, have been considered in the least-squares fits to the observed wavenumbers in order to derive reliable spectroscopic parameters. The spectral analyses deliver very precise B 0 and D 0 parameters and experimental values of the anharmonicity constants for the bending–bending combination states of diacetylene below 1000?cm-1.

Notes
vibration–rotation bands, diacetylene - hot: bands - anharmonicity: constants - resonances

Molecular Physics
Volume 109, Number 17-1, Page 2181
2011 August

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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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