The Microwave Spectrum and Ground State Structure of H2O-HI

Published

October 12, 2021

Author(s)

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

Abstract

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, χ_aa = -1479.399(20) MHz,(χ _bb- χ_cc) = -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 θ_av = 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.

Citation

Journal of Molecular Spectroscopy

Pub Type

Journals

Keywords

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

Citation

Mcintosh, A. , Walther, T. , Lucchese, R. , Bevan, J. , Suenram, R. and Legon, A. (2021), The Microwave Spectrum and Ground State Structure of H₂O-HI, Journal of Molecular Spectroscopy (Accessed April 26, 2024)