Nan Jiang
10 minutes
Tip-Enhanced Raman Spectroscopy
A sharpened gold or silver scanning-probe tip concentrates the plasmonic hot spot into a volume a few nanometres across, so the enhanced Raman signal comes only from the region under the apex. Scanning the tip yields chemical maps with roughly 10 nm resolution, far past the optical diffraction limit, and in ultrahigh vacuum at low temperature can resolve sub-molecular features.