Practice question

SPR stands for Surface Plasmon Resonance, a physical optical phenomenon occurring at the interface of a thin noble metal film, typically gold, and a dielectric medium. Upon illumination with p-polarized light under conditions of total internal reflection, conduction electrons undergo collective oscillations called surface plasmons. The resonance angle is highly sensitive to refractive index changes near the metal surface. Biomolecular binding increases local mass and refractive index, shifting resonance. This principle enables real-time, label-free detection of biomolecular interactions and is extensively used in biosensor technology for kinetic analysis.