Brillouin study of acoustic phonon confinement in Ge O2 nanocubes

Abstract

Brillouin light scattering from several aggregates of monodisperse Ge O2 nanocubes has been measured. Six well-resolved spectral peaks are observed whose frequencies scale as 1L, where L is the cube edge length. A finite element analysis of the eigenvibrations of a free nanocube reveals that the peaks are due to acoustic phonon confinement. Simulations show that the lowest-energy mode has a predominantly torsionallike character. The elastic constants of the nanocubes are found to be much lower than those of bulk Ge O2. © 2007 American Institute of Physics.