Gallium nitride nanorods with a 15- 40 nm diameter and a 50-150 nm length have been synthesized in monodisperse spherical mesoporous silica particles (MSMSP) by high-temperature annealing the Ga2O3 precursor in ammonia. The template material (a-SiO2) was selectively removed by etching the composite MSMSP/GaN particles in HF. The individual GaN nanorods were thus obtained. It is shown, that the size of GaN nanorods was much higher than the pore size of MSMSP (diameter ~3 nm, length ~10 nm). The possible mechanism of formation of GaN nanorods was proposed. Redistribution of material inside the composite particles MSMSP/GaN possibly occurred by surface diffusion of gaseous molecules in mesopores and by diffusion of Ga and N atoms in a-SiO2.
Luminescent hybrid spherical microresonators of two types consisting of monodisperse spherical silica particles with a diameter of 3.5 mcm coated with either FITC dye molecules or a 200 nm thick mesoporous silica shell containing DCM dye are fabricated. The luminescence spectra of microresonators are studied and the experimental emission spectra are simulated using the method of spherical wave transfer matrices. The ratio of intensities of emission lines into whispering gallery modes with different polarizations and the same polar and radial indices is analyzed. It is shown that the ratio depends on the orientation of the dipole moment of the radiative transition of dye molecules relative to the surface of spherical silica particles.
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