title: Isolating the spectroscopic signature of a hydration shell with the use of clusters: superoxide tetrahydrate
abstract: Cluster spectroscopy, aided by ab initio theory, was used to determine the detailed structure of a complete hydration shell around an anion. Infrared spectra of size-selected O(2)-. (H(2)O)(n) (n = 1 to 4) cluster ions were obtained by photoevaporation of an argon nanomatrix. Four water molecules are required to complete the coordination shell. The simple spectrum of the tetrahydrate reveals a structure in which each water molecule is engaged in a single hydrogen bond to one of the four lobes of the pi* orbital of the superoxide, whereas the water molecules bind together in pairs. This illustrates how water networks deform upon accommodating a solute ion to create a distinct supramolecular species.
authors.affiliation: Sterling Chemistry Laboratory, Yale University, Post Office Box 208107, New Haven, CT 06520-8107, USA.
authors.initials: JM
authors.lastname: Weber
authors.initials: JA
authors.lastname: Kelley
authors.initials: SB
authors.lastname: Nielsen
authors.initials: P
authors.lastname: Ayotte
authors.initials: MA
authors.lastname: Johnson