Brillouin study of confined eigenvibrations of silver nanocubes

The particle-size dependence of the eigenfrequencies of confined acoustic modes of aggregates of highly monodisperse silver nanocubes has been measured by Brillouin light scattering. Four Brillouin peaks are observed whose frequencies scale with inverse cube edge length. They are assigned to the D d 1 , D d 2 , D s 1 (symmetric breathing vibration) and D s 2 dilatational modes, labeled using the Demarest classification scheme. The assignment, which is based on numerically simulated frequencies and displacement profiles of the modes, as well as their calculated scattering cross-sections, differs from those of earlier studies on nanocubes. The elastic moduli of the silver cubes, with mean edge lengths between 59–102 nm, are found to be comparable to those of the bulk material, indicating the absence of sample defects like pores and cracks.