Project Details
Projekt
Investigation of the static and dynamical structure-property-relationships of diamondoid cluster compounds through optical spectroscopy
Applicant
Professorin Dr. Marina Gerhard
Subject Area
Experimental Condensed Matter Physics
Term
since 2022
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 398143140
In order to tailor novel diamondoid cluster compounds for efficient white light generation (WLG), it is essential to comprehend the interrelation between the WLG mechanism and the underlying micro- and nanostructure. Earlier work has unraveled that a high degree of amorphousness is required, whereas a certain degree of crystallinity seems to impede the process. The goal of this project is to complement existing methods of structural characterization by optical techniques such as absorption, photoluminescence and Raman spectroscopy.Optical spectra are particularly sensitive to intermolecular interactions and can thus provide information about the underlying local nanomorphology, ideally combined with theoretical work. Moreover, we will explore the optical properties through spatial mapping on a length scale > 1 µm by photoluminescence microscopy.Beside static order and disorder, we will also explore the dynamic properties of the condensed phase such as lattice vibrations, rotation of the ligands or conformational changes in the excited state. Since the mechanism of white light generation was only observed for the interaction of light with the electronic ground state, it is of particular relevance to make a distinction between the ground and excited state and to address both in spectroscopic experiments. Therefore, besides probing the intrinsic optical signatures of the compounds, we will also study samples with small luminescent molecules which can be excited at energies well below the absorption edge of the cluster compounds and which will therefore serve as probes for the local environment. The studies of the dynamical properties will also include investigations of the interaction between electronic excitations and lattice vibrations. In this context, low temperature and temperature dependent optical experiments are of particular relevance and the temperature-induced broadening of emission lines as well as the low temperature spectra will yield important quantities to estimate the electron-lattice interactions, which will be further compared to theoretical work. Also the presence of phonon side bands in emission spectra can be informative about the energies of the dominant vibrational modes. To probe these, it will most likely be necessary to remove the impact of inhomogenous broadening from emission or absorption spectra with optical line narrowing techniques.Overall, we intend to establish optical spectroscopy as an additional probe for the morphology of the growing library of cluster compounds, which will ideally pave the way for a more targeted research of compounds with improved WLG properties.
DFG Programme
Research Units
