Surface Plasmon Resonance (SPR). Surface Plasmon. Surface electromagnetic waves that propagate in a direction parallel to the metal/dielectric (or metal/vacuum) interface.
- Localized surface plasmon resonance (LSPR) for nanometer-sized metallic structures.
When phases of two waves are coincident, resonance occurs, resulting in minimum reflectivity
SPS excitation with a prism (Kretschmann configuration), then the observation of plasmon is possible:
the metal film is thin enough to monitor the plasmons from the backside
SPS excitation with a prism (Otto configuration): observation of the plasmon is impossible through infinite metal
If the thickness of the metal film varies, the phase difference between the reflected light and the light re-radiated by SP's will change, and for some "magical" thickness of the evaporated gold (48nm!) they will become completely out of phase and almost equal in amplitude. Thus they will destructively interfere, no light will come out
- Binding affinity
- Resonance angle shift of 0.1o : 1 ng/mm 2
- Detection limit of protein : 1.2 ng /cm 2