I am working on my course project titled " Laser induced assembly of gold nano particles into colloidal crystals". We are synthesising gold nano particles by nanopulsed laser(Nd-YAG second harmonic) ablation. How Laser parameters - wavelength,pulse width,fluence,repetition rate,scanning time affects the size and efficiency of the nanoparticles and which are the values for these factors to get maximum efficiency? we need to get nanoparticles have an average size less than 20nm.please help me.