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The Microwave Spectrum and Ground State Structure of H2O-HI



A McIntosh, T Walther, R R. Lucchese, J W. Bevan, R D. Suenram, A C. Legon


The microwave spectrum and ground state structure of H^2O HI are reported. The fitted ground state constants include: A0=428.9 GHz, B0=2189.7351(10) MHz, C0=2175.9546(10) MHz, χaa = -1479.399(20) MHz,(χ bb- χcc) = -17.37(2) MHz. Evidence will be presented for a complex that has an effective ground state planar geometry with an R(O-I) distance=3.745(4) Angstrom}, assuming no change in the geometry of the monomer components on complex formation. The reduction of χ aa from the value χ 0 in the free HI molecule, corresponds to a zero-point oscillation angle θav = cos-1 (2 θ>1/2) = 20.89(4) . The value of k α = 6.64(2) N m-1 evaluated from the available data indicates that the complex H2O?HI is more weakly bound than other members of the homologous series H2O HX (X=F, Cl, Br). Ab initio calculations have also been used to predict an equilibrium structure that is non-planar with a barrier to planarity of only 23 cm-1 in the H2O?HI hydrogen-bonded structure. No evidence was found experimentally for the isomeric form H2O?IH in the current studies.
Journal of Molecular Spectroscopy


ab initio calculation, Fourier transform microwave spectrum, molecular beam spectroscopy, molecular structure, rotational spectrum, van der Waals complex, vibrational spectrum, water-hydrogen iodide


Mcintosh, A. , Walther, T. , Lucchese, R. , Bevan, J. , Suenram, R. and Legon, A. (2021), The Microwave Spectrum and Ground State Structure of H<sub>2</sub>O-HI, Journal of Molecular Spectroscopy (Accessed July 25, 2024)


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Created October 12, 2021