title: Characterization of the primary hydration shell of the hydroxide ion with H2tagging vibrational spectroscopy of the OH-⋅ (H2O)n=2,3and OD-⋅ (D2O)n=2,3clusters.
abstract: We report the isotope-dependent vibrational predissociation spectra of the H2-tagged OH-⋅ (H2O)n=2,3clusters, from which we determine the strongly coordination-dependent energies of the fundamentals due to the OH groups bound to the ion and the intramolecular bending modes of the water molecules. The HOH bending fundamental is completely missing in the delocalized OH-⋅ (H2O) binary complex but is recovered upon adding the second water molecule, thereby establishing that the dihydrate behaves as a hydroxide ion solvated by two essentially intact water molecules. The energies of the observed OH stretches are in good agreement with the values predicted by Takahashi and co-workers [Phys. Chem. Chem. Phys. 17, 25505 (2015); 15, 114 (2013)] with a theoretical model that treats the strong anharmonicities at play in this system with explicit coupling between the bound OH groups and the O-O stretching modes on an extended potential energy surface. We highlight a surprising similarity between the spectral signatures of OH-⋅ (H2O)3and the excess proton analogue, H3O+⋅ (H2O)3, both of which correspond to completed hydration shells around the proton defect. We discuss the origin of the extreme solvatochromicity displayed by both OH-and H+in the context of the anomalously large "proton polarizabilities" of the H5O2+and H3O2-binary complexes.
authors: Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA.
authors: Olga
authors: O
authors: Gorlova
authors: Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA.
authors: Joseph W
authors: JW
authors: DePalma
authors: Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA.
authors: Conrad T
authors: CT
authors: Wolke
authors: College of Science and Mathematics, University of the Virgin Islands, St. Thomas, Virgin Islands 00802, USA.
authors: Antonio
authors: A
authors: Brathwaite
authors: Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15620, USA.
authors: Tuguldur T
authors: TT
authors: Odbadrakh
authors: Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15620, USA.
authors: Kenneth D
authors: KD
authors: Jordan
authors: Department of Chemistry, University of Washington, Seattle, Washington 98195, USA.
authors: Anne B
authors: AB
authors: McCoy
authors: Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA.
authors: Mark A
authors: MA
authors: Johnson