Effect of laser irradiation on the early-stage seed formation of laser-induced submicrometer-scale silica spheres.

We describe the effect of irradiation on the early-stage seed formation of submicrometer-scale (SS) SiO2spheres by a laser-induced process. A quartz cell containing chemical reagents was exposed to a pulsed laser (Nd:YAG, 532 nm) tuned to various energy densities, while SiO2SS spheres are synthesized in the quartz cell by the Stöber, Fink, and Bohn method. Higher laser energy densities typically produce wider size distributions. In particular, bidisperse SiO2spheres were obtained when the laser energy density was 1.15 J/cm2. The size distributions were widest with 1.15 J/cm2and narrowest with 0.33 J/cm2laser energy density. However, the compositions of the SiO2SS spheres were not affected by laser irradiation, and we observed by the energy-dispersive X-ray spectroscopy that the compositions of the irradiated and nonirradiated SiO2SS spheres were the same. [ABSTRACT FROM AUTHOR]