Project B1: Optical Spectroscopy of Condensed-Phase (Hetero-) Diamondoid Systems

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This project studies the photonic properties of the broadband emission in functionalized diamondoid clusters which are relevant for the identification of its fundamental microscopic origin on the one hand and for the implementation into device applications on the other. The latter, in particular, are the optical beam parameters like the spectral luminosity including its angular distribution, the temporal coherence as well as the spatial coherence, and the brilliance of the emission. These data will be acquired for a model functionalized adamantane-type cluster system of the general formula [(RT)4M6] (R = organic ligand; T = e.g., Sn or C; M = e.g., S or C), which can be handled and processed most easily. Currently, the prime candidates are bromine functionalized adamantanes. Here, photochemical amorphization has proved particularly successful for Br2Ph2Ad; however, the project will react to the ongoing developments in the other projects of FOR 2824. Ideally, these data lead to the identification of the mesoscopic structure-property relationship, i.e., on optical length scales. As these compounds can adopt varying degrees of crystallinity, the correlation of the structural materials properties with the photonic quantities will be established. Studying the coupling of the (e.g., ) electron systems in the ligands to the backbone of the molecules further clarifies the nature of the emission process. In particular, any potential equilibration behaviour of the electronic temperature and the lattice temperature and validity of the Born-Oppenheimer approximation in these systems will be explored to clarify, to what extent – if any – the origin of the continuum emission is thermal. This will contribute to the microscopic understanding of the origin and nature of the observed optical nonlinearities by spectroscopic means, i.e., monitoring vibrational excitations including their time evolution and clarify, to what extent transitions between electronic excitations of the individual molecules contribute.