Light, Tips and Molecules: SPM on the Path to Direct Nano-Optical Measurements

PC Department Seminar
Date: Jul 12, 2023
Time: 11:00 AM (Local Time Germany)
Speaker: Martin Švec
Czech Academy of Sciences
Location: Building G
Room: 2.06
Host: Akitoshi Shiotari

Exploration of essential photophysics at the level of individual molecules and atoms requires highly specialized optical spectroscopies that work at the very limit of instrument sensitivity or have to use plasmonic nanostructures - in order to overcome the fundamental resolution limits achievable with visible and infrared light.

Recent developments emerging in the field of Scanning Probe Light Microscopy (SPM) bring the unique opportunity to pursue intriguing, often hard-to-access interactions between light and matter at submolecular scale, with the finesse characteristic for the method based on atomically-sharp tips.
Plasmonic nanocavity formed naturally between the tip and sample of an SPM instrument enables a massive enhancement of the light field coupling to the studied objects, and therefore visualization of the fascinating inner processes of nanoscopic emitters. The modes of operation can be switched between the electroluminescence, photoluminescence and tip-enhanced Raman spectroscopies. We complement these optical measurements with the STM, STS and AFM data¹ to probe the eigenmodes, charges, vibronics and temporal evolution of the transient states in molecular emitters. Using this approach we have investigated the phenomena of single-photon generation in electrical fields,² quasiparticle delocalization over excitonic nanoclusters,³ vibronic coupling to electronic transitions⁴ and found a correlation between the spin crossover and Raman spectra of a molecular break junction.

References
[1] J Doležal et al., Nano Lett. 19, 8605-861 (2019)
[2] J Doležal et al., ACS Nano 15, 7694–7699 (2021)
[3] J Doležal et al., ACS Nano 16, 1082-1088 (2022)
[4] J Doležal et al., Nature Comm. 13, 6008 (2022)