Etude vibrationnelle du fluorure hydrogenodifluorure de baryum BaF(HF2) |
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Authors: | A Lautie F Romain M -H Limage A Novak |
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Institution: | Laboratoire de Spectrochimie Infrarouge et Raman, CNRS, 2 rue H. Dunant 94320 Thiais France Université des Sciences et Techniques du Languedoc 34060, Montpellier France |
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Abstract: | Infrared and Raman spectra of the BaF(HF2) crystal and its 10 and 50% deuterated derivatives at 300 and 90 K have been investigated in the 4000 to 20 cm−1 range. An assignment of internal and lattice vibrations has been proposed. Vibrational spectra are consistent with a centrosymmetric P21/m space group and Z=2. They show that the (FHF)− ion is not centrosymmetrical, in spite of a short F…F distance; a force field calculation has been performed in order to determine the F---H and H…F distances, which are equal to 1.08 and 1.20 Å, respectively, in agreement with the 1H and 19F NMR data. The ν3(H)/ν3(D) isotope frequency ratio indicates a negative or zero isotope effect on the F…F distance, which is observed for the first time for a strong asymmetric hydrogen bond. |
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