Surface plasmon resonance sprectroscopy (SPR)

Surface plasmon resonance (SPR) spectroscopy can be used in similar principle to the method of the quartz crystal micro balance (QCM) to monitor or detect changes in thickness on a surface . It uses a gold surface as a model surface, the surface plasmons can be excited by light.
The modification of the plasmon energy can give qualitative conclusions about the thickness and the possible adsorption of molecules or layers on the surface.