Single-molecule-resolution ultrafast near-field optical microscopy via plasmon lifetime extension
Ramazan Şahin, PhD · · 1 min read · Updated
A quantum emitter at the tip apex extends the plasmon lifetime so that ultrafast near-field signals come from a molecule-sized spot.
Plasmon oscillations on metal nanostructures usually die out very fast, but they can last longer when a longer-lived particle such as a molecule sits nearby. This paper proposes turning that effect into a tool for ultrafast apertureless (scattering-type) near-field microscopy with single-molecule resolution, and demonstrates it with numerical solutions of the three-dimensional Maxwell equations.
In the proposed set-up a nanometre-sized quantum emitter is attached to the very end of an AFM tip coated with metal, and the tip is illuminated by a femtosecond laser. The near field of the metal fades quickly, so after a short delay the scattered signal comes only from the surroundings of the emitter and the resolution becomes the size of the emitter itself. As the emitter, the authors suggest a strain-induced defect centre in a 2D material, created when the tip is pressed into the material so that the defect ends up right at the tip's sharpest spot. The paper notes that the same approach could also serve chemical manipulation at the scale of a single molecule.
This summary is based on the paper's published abstract; the author list, journal and DOI are shown in the citation box.