Spectroscopic studies on fluorescent single molecules in organic condensed matter does not only provide information about the molecule itself, but also its near environment. By suppression of... Show moreSpectroscopic studies on fluorescent single molecules in organic condensed matter does not only provide information about the molecule itself, but also its near environment. By suppression of phonon-induced broadening of spectral lines through cooling to low temperatures, small changes in the spectral lines’ position can be observed in response to weak variations in local fields. These variations can for instance be caused by rearrangements of charges or minute changes in the crystal lattice around the molecule. Therefore, molecules are sensitive sensors to what happens at the nanoscale. This is exemplified by coupling to an external electric field, inducing a Stark shift of the molecule’s spectral lines, as shown in Chapter 4. Other dynamics, related to the crystal around the molecule, are resolved in the fluorescence of molecules on the surface of two-dimensional hexagonal boron nitride, shown in Chapter 5. In Chapter 2, 3 and 6, perylene molecules are studied in a new host crystal with the aim of detecting a ‘forbidden’ transition to the triplet state from the ground state, a transition required for building a single-molecule optical switch. Show less
Single-molecule spectroscopy has become a powerful method for using organic fluorescent molecules in numerous applications. Along with sensing applications in biology and solid-state physics or a... Show moreSingle-molecule spectroscopy has become a powerful method for using organic fluorescent molecules in numerous applications. Along with sensing applications in biology and solid-state physics or a variety of applications in quantum information technology, molecules offer interesting possibilities for fundamental research. One of the very interesting areas is the study of charge transport and electric field sensing at the nanoscale. Developing molecular nanosensors for electric fields can not only help to fundamentally explore the motion of charges in conductors and semiconductors but can also lead to very sensitive and accurate instruments for quasi-static charge tracing or even single-electron charge detection. Such research could eventually lead to the construction of precise electric field sensors that can act as an interface between the quantum state of an electron and the outside word. We developed fluorescence molecular systems and electronic circuits with the aim of electric-field sensing and optical detection of one single electron. Show less
