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Theoretical IR spectra for water clusters (H2O)n (n = 6-22, 28, 30) and identification of spectral contributions from different H-Bond conformations in gaseous and liquid water
Linköping University, Department of Physics, Chemistry and Biology, Physical Chemistry . Linköping University, The Institute of Technology.
Linköping University, Department of Physics, Chemistry and Biology, Physical Chemistry . Linköping University, The Institute of Technology.ORCID iD: 0000-0002-5341-2637
2006 (English)In: Journal of Physical Chemistry A, ISSN 1089-5639, Vol. 110, no 50, 13388-13393 p.Article in journal (Refereed) Published
Abstract [en]

The vibrational IR spectra in the O-H stretching region are computed for water clusters containing 6-22, 28, and 30 molecules using quantum-chemical calculations (B3LYP and an augmented basis set). For the cluster with 20 molecules, several different structures were studied. The vibrational spectrum was partitioned into contributions from different molecules according to their coordination properties. The frequency shifts depend on the number of donated/accepted H-bonds primarily of the two molecules participating in the H-bond, but also of the surrounding molecules H-bonding to these molecules. The frequencies of H-bonds between two molecules of the same coordination type are spread over a broad interval. The most downshifted hydrogen-bond vibrations are those donated by a single-donor 3-coordinated molecule where the H-bond is accepted by a single-acceptor molecule. The H-bonded neighbors influence the downshift, and their contribution can be rationalized in the same way as for the central dimer. Single donors/acceptors cause larger downshifts than 4-coordinated molecules, and the least downshift is obtained for double donors/acceptors. This result is at variance with the conception that experimental liquid water spectra may be divided into components for which larger downshifts imply higher H-bond coordination. A mean spectral contribution for each coordination type for the donor molecule was derived and fitted to the experimental liquid water IR spectrum, which enabled an estimation of the distribution of H-bond types and average number of H-bonds (3.0 ± 0.2) in the liquid. © 2006 American Chemical Society.

Place, publisher, year, edition, pages
2006. Vol. 110, no 50, 13388-13393 p.
National Category
Natural Sciences
URN: urn:nbn:se:liu:diva-36614DOI: 10.1021/jp066372xLocal ID: 31825OAI: diva2:257463
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2015-03-09
In thesis
1. Theoretical Investigations of Water Clusters, Ice Clathrates and Functionalized Nanoparticles
Open this publication in new window or tab >>Theoretical Investigations of Water Clusters, Ice Clathrates and Functionalized Nanoparticles
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Nanosized structures are of intermediate size between individual molecules and bulkmaterials which gives them several unique properties. At the same time their relative limitedsizes make them suitable for studies by the methods of computational chemistry. In this thesiswater clusters, ice clathrates and functionalized metal-oxide nanoparticles have been studiedby quantum-chemical calculations and statistical thermodynamics.

The stabilities of water clusters composed of up to 100 molecules have been investigated. Themultitude of possible H-bonded topologies and their importance for determining theproperties of the clusters have been highlighted. Several structural characteristics of thehydrogen bonded network have been examined and the structural factors that determine thestability of an H-bonded network have been identified. The stability of two kinds of oxygenframeworks for water clusters have been analyzed, taking into account thermal energy andentropy corrections. Clusters with many 4-coordinated molecules have been found to be lowerin energy at low temperatures whereas the clusters with less-coordinated molecules dominateat higher temperatures. The equilibrium size distribution of water clusters as a function oftemperature and pressure has been computed using statistical thermodynamics. Themicroscopic local structure of liquid water has been probed by utilizing information from thestudied water clusters. The average number of H-bonds in liquid water has been predicted byfitting calculated average IR spectra for different coordination types in water clusters toexperimental IR spectra.

Water can form an ice-like structure that encloses various molecules such as methane. Thesemethane hydrates are found naturally at the ocean floor and in permafrost regions and canconstitute a large unemployed energy resource as well as a source of an effective green-housegas. The pressure dependencies of the crystal structures, lattice energies and phase transitionsfor the three methane hydrates with the clathrate structures I, II and H have been mapped out.

Zinc oxide is a semiconducting material with interesting luminescence properties that can beutilized in optical devices, such as photodetectors, light emitting devices and biomarkers. Theeffect of water molecules adsorbed on the ZnO surface when adsorbing organic acids havebeen investigated. Changes in optical properties by the adsorption of carboxylic acids havebeen studied and compared with experimental results. Aromatic alcohols at TiO2 metal-oxidenanoparticles have been studied as model systems for dye-sensitizied solar cells. Adsorptiongeometries are predicted and the influence from the adsorbed molecules on the electronicproperties has been studied.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2009. 52 p.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1254
National Category
Other Basic Medicine
urn:nbn:se:liu:diva-52746 (URN)978-91-7393-636-1 (ISBN)
Public defence
2009-06-09, Planck, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 10:15 (Swedish)
Available from: 2010-01-18 Created: 2010-01-12 Last updated: 2015-03-09Bibliographically approved

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