Size-Resolved Photoelectron Anisotropy of Gas Phase Water Clusters and   Predictions for Liquid Water
  We report the first measurement of size-resolved photoelectron angular distributions for the valence orbitals of water clusters with up to 20 molecules. A systematic decrease of the photoelectron anisotropy is found for clusters with up to 5-6 molecules, and most remarkably, convergence of the anisotropy for larger clusters. We suggest the latter to be the result of a local short-range scattering potential that is fully described by a unit of 5-6 molecules. The cluster data and a detailed electron scattering model are used to predict liquid water anisotropies. Reasonable agreement with experimental liquid jet data is found. 
Sebastian Hartweg, Bruce L. Yoder, Gustavo A. Garcia, Laurent Nahon,   and Ruth Signorell
physics.chem-ph