Tip-Enhanced Raman Spectroscopy: Nanoscale Hot-Spot Scanning

Tip-enhanced Raman spectroscopy (TERS) turns an ordinary metal AFM/STM tip into a scanning plasmonic antenna: bringing the sharp apex within a nanometre of a molecule squeezes the local optical field into a "gap-mode" hot spot, boosting the normally faint Raman signal by many orders of magnitude while confining it to a region far smaller than the laser's diffraction-limited spot. This simulator models that gap-mode enhancement from first principles — a dipole near-field falloff with tip radius and gap, doubled by image-charge coupling to the substrate, and weighted by a Lorentzian plasmon-resonance curve in wavelength — and lets you drive an actual raster scan across a row of molecules, building a live super-resolved Raman image so you can see the trade-off between enhancement strength and spatial resolution first-hand.