Gigahertz Frame Rate Imaging of Charge-Injection Dynamics in a Molecular Light Source

Light sources on the scale of single molecules can be addressed and characterized at their proper sub-nanometer scale by scanning tunneling microscopy-induced luminescence (STML). Such a source can be driven by defined short charge pulses while the luminescence is detected with sub-nanosecond resolution. We introduce an approach to concurrently image the molecular emitter, which is based on an individual defect, with its local environment along with its luminescence dynamics at a resolution of a billion frames per second. The observed dynamics can be assigned to the single electron capture occurring in the low-nanosecond regime. While the emitter's location on the surface remains fixed, the scanning of the tip modifies the energy landscape for charge injection into the defect. The principle of measurement is extendable to fundamental processes beyond charge transfer, like exciton diffusion.

Automated summary

Researchers have successfully addressed and characterized light sources on the scale of single molecules using scanning tunneling microscopy-induced luminescence (STML), achieving high-resolution observation of the dynamics of single molecule emission. They observed that single electron capture occurs in the low-nanosecond regime, while scanning of the tip affects the energy landscape for charge injection into the defect. The measurement principle can be extended to fundamental processes beyond charge transfer, such as exciton diffusion.