Effect of mega-hertz repetition rate on the agglomerated particle size of femtosecond synthesized nanostructures

We report a unique study performed on the modal transition laser fluence of agglomerated nanoparticle size distributions and their averages in three-dimensional nanostructures that were formed on aluminosilicate ceramic using a megahertz femtosecond laser. At low repetition rates, bimodal particle distributions were obtained and changed to unimodal distributions with the increase in repetition rate. The distribution modals obtained depend only on the laser fluence and the presence of photoionized species were the possible reason for the formation of bimodal distributions. Laser fluence and heat accumulation could have played key roles in determining the average particle sizes. Our study would help to enhance the properties of 3-D agglomerated nanostructures.