Nonlinear optical behavior of silver nanopentagons

•Novel silver nanopentagons were prepared by liquid-phase method.•The silver nanopentagons exhibited intensity-dependent transformation from saturable absorption (SA) to reverse saturable absorption (RSA).•The transformation from SA to RSA is also found to be highly dependent on the shape and morphology of the silver nanoparticles.

Novel silver nanopentagons were prepared by a liquid-phase method. Their nonlinear optical properties were investigated by open aperture Z-scan technique using 8 ns laser pulses at 532 nm. The silver nanopentagons exhibited intensity-dependent transformation from saturable absorption (SA) to reverse saturable absorption (RSA). The SA behavior may be attributed to the bleaching of ground-state surface plasmon resonance absorption. By contrast, the RSA may have resulted from high excited-state free carrier absorption and nonlinear scattering. The transformation from SA to RSA is also found to be highly dependent on the shape and morphology of the silver nanoparticles.