title: A fully size-resolved perspective on the crystallization of water clusters.
abstract: The number of water molecules needed to form the smallest ice crystals has proven challenging to pinpoint experimentally. This information would help to better understand the hydrogen-bonding interactions that account for the macroscopic properties of water. Here, we report infrared (IR) spectra of precisely size-selected (H(2)O)(n) clusters, with n ranging from 85 to 475; sodium doping and associated IR excitation-modulated photoionization spectroscopy allowed the study of this previously intractable size domain. Spectral features indicating the onset of crystallization are first observed for n = 275 ± 25; for n = 475 ± 25, the well-known band of crystalline ice around 3200 cm(-1) dominates the OH-stretching region. The applied method has the potential to push size-resolved IR spectroscopy of neutral clusters more broadly to the 100- to 1000-molecule range, in which many solvents start to manifest condensed phase properties.
authors.affiliation: Institut für Physikalische Chemie, Universität Göttingen, Tammannstr. 6, D-37077 Göttingen, Germany.
authors.forename: Christoph C
authors.initials: CC
authors.lastname: Pradzynski
authors.forename: Richard M
authors.initials: RM
authors.lastname: Forck
authors.forename: Thomas
authors.initials: T
authors.lastname: Zeuch
authors.forename: Petr
authors.initials: P
authors.lastname: Slavíček
authors.forename: Udo
authors.initials: U
authors.lastname: Buck