Berlin, Techn. Univ., Diss., 2003. / Computerdatei im Fernzugriff.

Berlin, Techn. Univ., Diss., 2003. / Computerdatei im Fernzugriff.

Berlin, Humboldt-Universiẗat, Diss., 2000.

Bielefeld, Universiẗat, Diss., 2002.

Techn. Universiẗat, Diss., 2003--Berlin.

Water aerosols affect the climate because they have an impact on the radiation balance and cloud formation. Water is present in all forms in the atmosphere (water, ice and steam), for example as rain and hail. Water aerosols play an important role in many biological and chemical processes in the atmosphere. The most common form of water in the atmosphere is water droplets or vapor which often come from oceans and lakes and these aerosols often contain organic compounds. It is therefore interesting to study if organic compounds, in this case glycerol, will reside on the surface or inside the water droplets. The investigations were performed by using theoretical studies, molecular dynamic simulations in GROMACS, and experimental investigations; X-ray photoelectron spectroscopy with a liquid jet. The experiments were performed at BESSY II, Berlin. The concentrations of glycerol were varied from 75:1; 8:1 to 4:1 (water: glycerol molecules). The results were that the experiments and simulations indicated that when theconcentration of glycerol increased the glycerol concentration at the surface of the waterdroplet increases until a monolayer of glycerol molecules was formed at the surface. When the monolayer was formed (or close to) less and less glycerol molecules were placed at thewater surface and more and more glycerol molecules were placed in the bulk of the waterdroplet. / Vattenaerosoler påverkar klimatet eftersom de har en inverkan på strålningsbalansen och molnbildningen. Vatten finns i alla former i atmosfären (vatten, is och ånga) som bland annat regn och hagel. Vatten aerosolerna spelar en viktig roll i många kemiska och biologiska processer i atmosfären. Den vanligaste formen av vatten i atmosfären är små vattendroppar eller ånga som ofta kommer från hav och sjöar och som ofta innehar organiska föreningar. Då vattenaerosoler påverkar klimatet och organiska föreningar är vanligt förekommande i vattendroppar är det intressant att undersöka om organiska föreningar, i detta fall glycerol, hamnar på ytan eller inuti vattnet. Undersökningarna har gjorts genom att använda teoretiska perspektiv, molekylärdynamiska simuleringar i GROMACS, samt experimentella undersökningar i form av röntgen fotoelektronspektroskopi med en vätskejet. Dessa experiment utfördes i BESSY II, Berlin. Koncentrationerna av glycerol varierades från75:1; 8:1 till 4:1 (vatten: glycerolmolekyler). Resultaten från experimenten och simuleringarna indikerade att när koncentrationen av glycerol ökade så ökade glycerolkoncentrationen på ytan av vattendroppen tills det bildades ett monolager av glycerolmolekyler på vattenytan. När monolagret hade bildats så placerades mindre och mindre glycerolmolekyler på vattenytan och fler och fler glycerolmolekyler placerades inne i vattendroppen.

Clusters/nanoparticles are aggregates of a “small” number of building blocks, atoms or molecules, ranging from two up to millions of atoms. Two main groups of clusters have been studied using photoelectron spectroscopy based on synchrotron radiation. They are dry/wet alkali-halide clusters, including pure water clusters, and metal-based nanoparticles. For the dry alkali halide clusters, analysis of the data and theoretical modeling has allowed us insights into the local electronic properties at nanoscale: a change of polarizability of ions in the alkali-halide clusters due to the varying environment has been suggested. The study of the wet salt clusters shows that the alkali-halides are already solvated at the nanoscale reached by water clusters doped with salt vapor. The photoelectron angular distribution of water cluster shows lower anisotropy parameters as compared to the separate monomers. A model based on intracluster scattering has been built to partly explain the reduction. In the last part of the thesis, metal-based multi-component nanoparticles have been produced by self-assembly processes using reactive magnetron sputtering. Depending on the specific metal element, oxidation processes have been applied before or after the aggregation. Clearly radial distributions such as core-shell and “sandwich-like” structures have unambiguously determined by photoelectron spectroscopy.

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