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.