Photo-fragmentation of selenium powder by Excimer laser ablation in liquids

Laser ablation in liquids is especially adapted to produce nanoparticles free of any contamination as suited for biological and medical applications. A KrF Excimer laser delivering an UV light at 248nm and operating at low fluence (F~0.5J/cm2) was used to irradiate a micro-sized powder of selenium dispersed into a de-ionized water solution. To avoid any agglomeration of the selenium nanoparticles during the irradiation, surfactants (SDS and CTAB) were added to the solution and their efficiency was compared. The concentration of surfactants had to be chosen around the critical micellar concentration to produce small selenium nanoparticles (<60nm). Moreover, SDS shows better mono-disperse size distribution compared to CTAB. Finally, photo-fragmentation is found to be more efficient than bulk thermal ablation to produce very small selenium nanoparticles (less than 10nm).