Plasmons with a purpose
Exploited unknowingly by craftsmen for hundreds of years, the plasmonic effects of metal surfaces have rapidly gone from curiosity to treating cancer. Andy Extance trips the light fantastic
Artists and craftsmen have unknowingly made use of plasmons for at least 1600 years, by colouring glass objects with metal particles (such as the Lycurgus cup). In the 19th century, Michael Faraday systematically studied the synthesis and appearance of colloidal gold. But researchers didn’t identify their underlying colour-controlling surface plasmonic principles until the 1950s. At first, interest centred on intense electromagnetic fields associated with surface plasmons. As the fields’ properties depend upon the environment near a metal surface, adsorption of small molecules causes detectable changes, which were soon exploited in surface plasmon resonance spectroscopy. These electromagnetic fields also enabled single-molecule sensitivity in surface-enhanced Raman scattering spectroscopy (SERS).