Plasmon Scattering Microscopy (IMAGE) Arizona State University Caption When protein molecules (purple) bind to immobilized receptor molecules, (like the Y-shaped antibodies affixed to the slide surface), the refractive index at the gold surface changes, altering the surface plasmon resonance condition, and producing an increase in signal intensity. Credit Graphic by Shireen Dooling Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.