Nanoparticles from the vapor phase: Synthesis and characterization of Si, Ge, MoO3, and WO3 nanocrystals

In this paper, we present two studies of nanocrystals prepared by the pulse d laser vaporization-controlled condensation (LVCC) technique. In the first study, we present a comparison between the surface oxidation, morphology a nd the photoluminescence (PL) properties of Si and Ge nanocrystals. In the second study, we compare the photochromic properties of Mo and W oxides nan oparticles with the properties of the corresponding bulk materials. We also present evidence for a novel photoreduction of the white WO3 nanoparticles into the blue W2O5 following the irradiation of the particles with the sec ond harmonic of the Nd:YAG laser in air. These studies illustrate the novel properties of the nanoscale particles, which could lead to significant pra ctical and technological applications.