Configurational Control of Photon Emission from a Molecular Dimer

High Resolution Image Download MS PowerPoint Slide Quantum technology relies on mastering devices on the atomic and molecular scale by external stimuli. Here, using the interconversion of bistable configurations of tin phthalocyanine molecules residing above ultrathin rock-salt islands on Au(111) by locally injecting electrons from the tip of a scanning tunneling microscope, a molecular dimer is shown to act as a photon source with reversibly switchable intensity. A rationale for the high and low photon yields is suggested by the fluorescence fine structure of the dimer, which can be attributed to the coherent coupling of optical transition dipoles. The electroluminescence spectrum of the molecular monomer is characterized instead by vibrational progression and hot luminescence due to vibrational excitation.