Optical absorbance of silver ellipsoidal particles

We have studied the optical absorbance of silver ellipsoidal particles with parallel principal axes. A simple technique for producing arrays of silver particles in this configuration is described. The particles were characterized by scanning electron microscopy. The optical absorbance of the silver ellipsoids produced by this technique was measured as a function of wavelength, polarization, and incident angle of the incident light. Theoretical analysis of the response of these objects was made using nonretarded electrodynamics and the bulk optical constants for silver. The dipole approximation was assumed. The results indicate that resonant surface-plasmon modes are stimulated along the principal axes of the ellipsoids and contribute to the absorbance. The calculations are shown to compare favorably with the measurements.