Abstract

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.

Highlights

  • 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)

  • The individual charges during redox reactions, biosynthesis, and light emission from optoelectronic devices undergo a series of processes like tunneling, hopping, or recombination leading to measurable chemical, electronic, or optical signals.[1,2]

  • This limitation can be overcome by using advanced methodologies like allelectronic pump−probe spectroscopy[12] or coupling with ultrafast laser pulses.[13−15] In such experiments, the signal is detected by employing the STM tunnel current to read out the averaged response of the system that varies with the delay between the applied pulses

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Summary

Author Contributions

All authors contributed to discussions and writing of the manuscript

■ ACKNOWLEDGMENTS
■ REFERENCES
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