Micro-Brillouin scattering from a single isolated nanosphere

Inelastic light scattering from a single isolated silica sphere, of diameter as small as $260nm$⁠, has been measured as a function of sphere size by micro-Brillouin spectroscopy. The feasibility of recording spectra of a sample as tiny as this, and for which only one particle is needed, further enhances the capabilities of Brillouin light scattering as a powerful investigative tool. Such measurements afford the evaluation of the elastic properties of single nanospheres and a determination of the size polydispersity of an aggregate of particles from the asymmetric broadening of its Brillouin spectrum. Unlike conventional Brillouin scattering from acoustic waves, what is observed here is the inelastic scattering from the eigenvibrations of a nanosphere.