Demonstration of variation of the nonlinear optical absorption of non-spherical silver nanoparticles

We study the features of the nonlinear optical response of silver nanoparticles (Ag NPs) of the spherical and triangular shapes synthesized using a citrate-borohydride approach. The Z-scans were used to analyze the nonlinear optical absorption of Ag NPs of different morphology, particularly, the concurrence of saturable and reverse saturable absorption in the solution containing triangular Ag NP. We show the significant contribution to the increase in the normalized transmittance accomplished by photochemical degradation of the non-spherical Ag NPs (extinction maximum of 600 nm) and transformation into the spherical ones (extinction maximum of 400 nm). The nonlinear light scattering is analyzed as well, which showed the contribution to the variation of the sample transmission when it approaches the focal plane.