title: A size resolved investigation of large water clusters.
abstract: Size selected water clusters are generated by photoionizing sodium doped clusters close to the ionization threshold. This procedure is free of fragmentation. Upon infrared excitation, size- and isomer-specific OH-stretch spectra are obtained over a large range of cluster sizes. In one application of this method the infrared spectra of single water cluster sizes are investigated. A comparison with calculations, based on structures optimized by genetic algorithms, has been made to tentatively derive cluster structures which reproduce the experimental spectra. We identified a single all-surface structure for n = 25 and mixtures with one or two interior molecules for n = 24 and 32. In another application the sizes are determined at which the crystallization sets in. Surprisingly, this process strongly depends on the cluster temperature. The crystallization starts at sizes below n = 200 at higher temperatures and the onset is shifted to sizes above n = 400 at lower temperatures.
authors.affiliation: Max-Planck-Institut für Dynamik und Selbstorganisation, Am Faßberg 17, 37077 Göttingen, Germany. ubuck@gwdg.de.
authors.forename: Udo
authors.initials: U
authors.lastname: Buck
authors.forename: Christoph C
authors.initials: CC
authors.lastname: Pradzynski
authors.forename: Thomas
authors.initials: T
authors.lastname: Zeuch
authors.forename: Johannes M
authors.initials: JM
authors.lastname: Dieterich
authors.forename: Bernd
authors.initials: B
authors.lastname: Hartke