P16372-N02: Analysis of nanometer-scale structures in condensed-phase systems using intermolecular resonant vibrational interactions

Dilution experiments in binary liquid mixtures of molecular liquids allow to observe many concentration dependent changes in the Raman band shape (position, width, asymmetry) of vibrational modes of molecules in the liquid mixtures. Among these changes, in the present project we will continue to pay attention to those arising from intermolecular resonant vibrational interactions, which are sensitive to molecular orientations. The Raman spectroscopically observable effects manifest themselves in the non-coincidence effect and in an asymmetry of the band shape, and provide information on “static” nanometer-scale structures (due to dipole-dipole and due to hydrogen-bonding interactions) and short-time dynamics, which will be clarified by theoretical analyses and by molecular dynamics simulations. The experimental work will be carried out in form of an already existing international cooperation between the Institute of Physics and Biophysics at the University of Salzburg (Austria) and the Department of Physical and Inorganic Chemistry at the University of Bologna (Italy), as a continuation of the collaboration established back in 1994. It will consist of the Raman spectroscopic study of effects of intermolecular resonant vibrational interactions on the band shape observed in the vibrational spectra of molecular liquids. At the same time theoretical investigations and computer simulations will be carried out at the Department of Chemistry of the Shizuoka University (Japan), extensively analyzing relative orientations of molecules in addition to their relative positions. Not only static structures but also short-time dynamics (on the pico- to nanosecond time scale) will be considered. Although the informal cooperation between the mentioned institutions was already started in 1996, the purpose of this project proposal is to establish a closer collaboration between the Japanese applicant and the Austrian applicant, including visits at each other laboratory for more extensive research work. The scientific target of this project proposal is to clarify the nanometer-scale structures formed by molecules coupled by resonant intermolecular vibrational interactions in soft condensed-phase systems, such as molecular liquids and biomolecular aggregates.These studies will be carried out in order to better understand the formation of nanometer-scale structures in biologically relevant environments, and the dependence of these structures on concentration and temperature.