  Here we describe an optical method to determine the dynamics of optically
excited carriers in nanostructured composite samples. By combining pump-probe
time-resolved reflectivity with scattering measurements, we extract the
characteristic times for charge carrier evolution. We use the 3D
Maxwell-Garnett formulae, modified to include the Drude optical response, to
model the results. The method, applied to hydrogenated amorphous silicon
containing crystalline silicon nanoparticles, showed that the recombination
times in the nanocrystals and in the matrix were ~4.9 ps and ~22 ps,
respectively. The charge transfer time between the crystals and the matrix was
~4 ps.
