《localized surface plasmon resonanse spectroscopy of single silver nanocubes》.pdf

NANO LETTERS Localized Surface Plasmon Resonance 2005 Vol. 5, No. 10 Spectroscopy of Single Silver Nanocubes Leif J. Sherry, Shih-Hui Chang, George C. Schatz,* and Richard P. Van Duyne* Chemistry Department, Northwestern Uniersity, 2145 Sheridan Road, E anston, Illinois 60208-3113 Benjamin J. Wiley and Younan Xia Department of Chemistry, Uni ersity of Washington, Seattle, Washington 98195 Received August 10, 2005 ABSTRACT In this work, we use dark-field microscopy to observe a new plasmon resonance effect for a single silver nanocube in which the plasmon line shape has two distinct peaks when the particles are located on a glass substrate. The dependence of the resonance on nanocube size and shape is characterized, and it is found that the bluer peak has a higher figure of merit for chemical sensing applications than that for other particle shapes that have been studied previously. Comparison of the measured results with finite difference time domain (FDTD) electrodynamics calculations enables us to confirm the accuracy of our spectral assignments. The optical properties of metal nanoparticles have been the only to dipolar excitations but also to higher-order multipolar subject of intensive research efforts because of their applica- excitations for certain nanoparticle structures.16 tions in research areas such a