Interfacial Velocity-Dependent Plasmon Damping in Colloidal Metallic Nanoparticles

Modulation of the surface plasmon resonance of colloidal silver nanoparticles driven by particle shape oscillations is interrogated via transient-scattering measurements using white light as the probe. The two-dimensional (λ, t) image of the spectrally resolved scattering shows π/2 phase shift between the modulation of center Ω(t) and width Γ(t) of the resonance − while Ω is modulated by the strain amplitude, the plasmon-damping rate Γ is modulated by the strain rate. We ascribe the effect to scattering from the electrophoretic potential generated by the motion of the interfacial double layer of the colloidal particles.