The formation of silica nano- and microparticles has been studied during growth by the modified Stöber-Fink-Bohn (SFB) method. It has been experimentally found that the density and fractal structure of particles vary with size as they grow from 70 to 2200 nm. We propose a model of particle structure which is a dense primary particle core and is composed of concentric secondary particle shells terminating in dense primary particle layers.

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Structural transition in II-VI nanofilms: Effect of molar ratio on structural, morphological, and optical properties J. Appl. Phys. 111, 113510 (2012) Emission from a dipole-forbidden energy state in a ZnO quantum dot induced by a near-field interaction with a fiber probe Appl. Phys. Lett. 100, 223110 (2012) Effect of Lorentz local field for optical second order nonlinear susceptibility in ZnO nanorod J. Appl. Phys. 111, 103112 (2012) A comparative study of ultraviolet photoconductivity relaxation in zinc oxide (ZnO) thin films deposited by different techniques J. Appl. Phys. 111, 102809 (2012) Additional information on J. Appl. Phys. We study photoluminescence ͑PL͒ of ZnO-opal structures excited by a 351.1 nm laser line. The structures were fabricated by infiltration of ZnO from an aqueous solution of zinc nitrate into opal matrices. The emission spectrum of thick ZnO layers grown on the surface of bulk opals exhibits narrow PL bands associated with the recombination of bound and free-excitons. The free-exciton lines are discussed taking into account the polariton phenomena. The width of the excitonic lines ͑2-3 meV͒ along with their energy position is indicative of high quality and strain-free state of the layer. The emission from ZnO crystallites embedded into bulk opal is dominated by near band gap luminescence, a weak quantum confinement effect being observed for crystallites with sizes around 50 nm. Thin ZnO films grown on single-layer opals exhibit enhanced resonant Raman scattering, phonon confinement effects, and surface-related modes. Strong exciton-LO phonon and exciton-Fröhlich mode coupling in ZnO nanostructures is deduced from the analysis of multiphonon excitonic resonant Raman scattering.

We report experimental and theoretical results on the photoluminescence of CdTeSe nanocrystals, embedded in a silica opaline structure by infiltration of a highly diluted solution. Strong modification of emission diagrams of embedded nanocrystals have been observed in good agreement with theoretical models. At macroscopic scale, we measured the difference of nanocrystals emission lifetime embedded either in an opal for which the emission is in the gap, or in an opal of smaller balls diameter for which the emission is outside the gap. The photonic bandgap effect leads to a lifetime increase of the order of 10%. These lifetime variations are shown to be in good agreement with the calculated local density of states modification due to the pseudogap.

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