Physics – Deciphering Single-Molecule Fluorescence
[ad_1]
• Physics 16, s31
Spatial maps of the sunshine emitted by an excited molecule reveal how the emission depends upon the molecule’s cost states.
Scanning tunneling microscopes (STMs) let physicists peer at particular person fluorescent molecules with close-to-atomic decision. However the detailed mechanism by which a molecule emits gentle below stimulation by an STM stays debated, as a result of observations don’t point out what spin and cost states the excited molecule transits by means of earlier than it decays to the bottom state. Offering key data towards resolving this debate, Tune Jiang, of the College of Strasbourg, France, and his colleagues have performed an experiment and developed a mannequin to narrate the molecule’s cost state to the emitted gentle vitality [1].
Within the workforce’s experiment, an STM tip drives a present throughout a quinacridone (QA) molecule adsorbed on a skinny insulating movie layered upon a metallic substrate. A uncommon property of QA is that its impartial and positively charged states have distinct emission patterns, with the orientation of the molecule’s fluorescent dipoles differing by 65 levels. Whereas scanning the fabric with an STM tip throughout totally different voltage ranges, the researchers created sub-nanometer-resolution fluorescence maps. From the patterns in these maps, they may decide the orientation of the dipole that fluoresced—and, therefore, the molecule’s cost state—at a given second. They then established a mannequin describing the main points of the electron transport and light-weight emission based mostly on the STM present and voltage in addition to on the spatial dependency of an STM-induced fluorescence sign.
The research demonstrates that, relying on the utilized voltage, a single molecule on a substrate can maintain 4 totally different cost states. It moreover gives a option to distinguish between phosphorescence and current-driven luminescence of charged molecules. The authors say the mannequin may be generalized to any natural system adsorbed on a skinny movie.
–Rachel Berkowitz
Rachel Berkowitz is a Corresponding Editor for Physics Journal Journal based mostly in Vancouver, Canada.
References
- S. Jiang et al., “Many-body description of STM-induced fluorescence of charged molecules,” Phys. Rev. Lett. 130, 126202 (2023).
Topic Areas
[ad_2]
