title: Rotational spectrum and hydrogen bonding of the H2O-HO radical complex.
abstract: The first spectroscopic identification of the H2O-HO radical complex in the gas phase has been conducted by utilizing pulsed-discharge nozzle Fourier transform microwave spectroscopy. R-branch transitions in the Ka = 0 manifold appeared as in Hund's case (b), but extraordinarily large spin doubling implies a strong spin-orbit coupling between the electronic ground and low-lying excited states that correlate to the degenerate 2Pi state in free OH. The geometry of the complex is of C2v symmetry as a zero-point vibrational average, in which the OH radical acts as a proton donor to water. Precisely determined hyperfine coupling constants associated with hydrogen nuclei indicate a substantial rearrangement in unpaired electron distribution: there exists small but nonzero spin density on the H atoms in water.
authors.affiliation: Institute for Molecular Science, Okazaki 444-8585, Japan, and Department of Pure and Applied Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo 153-8902, Japan. ohshima@ims.ac.jp
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ohshima
authors.forename: Kazuya
authors.initials: K
authors.lastname: Sato
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sumiyoshi
authors.forename: Yasuki
authors.initials: Y
authors.lastname: Endo