Basche is one of the founding figures of optical single-molecule spectroscopy. The group performs high-resolution fluorescence-excitation spectroscopy on single dibenzoterrylene (DBT) molecules in anthracene hosts at liquid-helium temperature, where zero-phonon lines approach the Fourier limit -- effectively a solid-state single-photon emitter with atom-like linewidths -- and studies how nanocrystal host engineering (e.g. electrohydrodynamic printing) preserves spectral stability, with polarization-resolved super-resolution imaging used to pin down crystal orientation. Further lines: photon-statistics and blinking in single quantum dots and QD/dye hybrids, and single-molecule studies of singlet fission, where photon-stream analysis of terrylenediimide dimers exposed coherent multiexciton superpositions that ensemble measurements average away. Relative to the established NV-ensemble quantum-sensing playbook (DEER, nanoscale NMR, T1 relaxometry at pT/sqrt(Hz) ensemble sensitivity), this is the molecular analogue of the colour-centre programme -- same photophysics toolkit (HBT, resonance fluorescence, orientation-resolved imaging), different emitter -- and it is the strongest single-emitter optics group in Mainz chemistry. Note: senior/long-established professor; confirm current group status and recruiting before applying.