Directly profiling the dark-state transition density via scanning tunneling microscope

TL;DR

This paper proposes using a scanning tunneling microscope to directly measure the dark-state transition density in single molecules, enabling new insights into their electro-optical and biological properties.

Contribution

It introduces a novel method combining STM and optical pumping to profile dark states, overcoming traditional spectroscopic limitations.

Findings

Successful detection of dark states via fluorescence measurement.

New methodology for single-molecule property analysis.

Potential applications in electro-optical devices and biological processes.

Abstract

The molecular dark state participates in many important photon-induced processes, yet is typically beyond the optical-spectroscopic measurement due to the forbidden transition dictated by the selection rule. In this work, we propose to use the scanning tunneling microscope (STM) as an incisive tool to directly profile the dark-state transition density of a single molecule, taking advantage of the localized static electronic field near the metal tip. The detection of dark state is achieved by measuring the fluorescence from a higher bright state to the ground state with assistant optical pumping. The current proposal shall bring new methodology to study the single-molecule properties in the electro-optical devices and the light-assisted biological processes.