Plasmon line widths of single silver nanoprisms as a function of particle size and plasmon peak position

We study the homogeneous line width of the plasmon resonance scattering peaks of anisotropic silver nanoparticles using single particle darkfield scattering spectroscopy. We correlate the scattering spectra with scanning electron microscopy images of the particles to investigate the effects of nanoparticle size on the plasmon line width. We observe that the scattering line widths of silver nanoprisms increase both as the particle volume increases and as the plasmon resonance energy increases. We attribute the size dependence to radiation damping and compare our data both to simple dipole-limit approximations for the radiative and nonradiative decay rates and with finite-difference time-domain (FDTD) calculations of the scattering line width. We find the data and calculations in good agreement for an appropriate choice of the bulk optical constants of silver and find that the dipole-limit approximations capture the observed size and energy-dependence of the plasmon line widths.