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978-3-8439-0645-6, Reihe Ingenieurwissenschaften
Benedikt Otmar Schürer
Application of Second Harmonic Scattering for the Characterisation of Colloidal Interfaces
160 Seiten, Dissertation Universität Erlangen-Nürnberg (2012), Softcover, A5
In this thesis, an experimental setup is presented that enables angle-resolved second harmonic (SH) scattering experiments with technically relevant particle systems. The SH light that is scattered by colloidal suspensions contains specific information about number, species and orientation of the respective interfacial molecules. However, so far the application SH light scattering was limited to a few model systems due to the very weak signal intensities and the missing theoretical and experimental basis. Several systematic experiments regarding the influence of different suspension parameters, such as the influence of particle size, species of interfacial molecules and particle concentration, are performed in order to establish the method for the characterisation of colloidal interfaces. By comparison of the experimental SH scattering profiles with simulations it becomes possible to derive specific information about the structure of the respective interfacial layer.
Based on the results of the fundamental studies several new applications of SH light scattering evolve. The intrinsic surface sensitivity of the method makes it possible to detect the adsorption of charged molecules, such as proteins and polyelectrolytes, at different hydrophilic and hydrophobic interfaces. In the case of electrosterically stabilised particles conformational changes within the shell layer can be inferred directly from changes of the SH scattering profiles. Furthermore, in situ studies of the transformation of titanate nanowires into nanoscrolls and of the growth of gold nanoshells on colloidal silica particles are presented. These measurements become possible be a combination of UV/Vis spectroscopy with SH scattering.