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Determination of Thickness Dependence of Surface Plasmon Resonance in Thin Silver Foils

Researchers: Timothy St. Claire and Andrea Walker

Advisor: Kevin Booth

During this semester we found studying Surface Plasmon Resonance (SPR) a challenging yet rewarding pursuit. SPR is an up and coming area of research due to its applications in biophysics, specifically as applied to developing new pharmaceutical products for cancer treatments. The theory of Surface Plasmon Resonance draws upon knowledge from multiple areas of physics: optics, electromagnetism, and solid state physics.What is SPR?Surface Plasmon Resonance refers to the the resonant oscillation of electrons across the boundary between an insulator and a conductor. This resonance is achieved by incident photons being absorbed by the electrons on the surface of the conductor. Absorption of the photon excites the electrons, initiating the resonance. This absorption happens under the specific condition of the electromagnetic wave of the photon coupling with the electromagnetic wave of the electron. How is SPR observed?Since SPR is excited by shining a laser onto a thin metal foil, a dark band in the reflected laser beam appears whenever the photons couple to and are absorbed by the electrons in the metal foil. Thus SPR is studied through observing and measuring the width and intensity of these dark bands. 1 Theory