Intensity-dependent enhancement of saturable absorption in PbS- Au 4 nanohybrid composites: Evidence for resonant energy transfer by Auger recombination

Abstract

Intensity-dependent enhancement of saturable absorption in a film of PbS- Au4 nanohybrid composites has been observed by femtosecond time-resolved transient absorption measurement at 780 nm. The nonlinear absorption coefficient (α2) of saturable absorption in PbS- Au4 nanohybrid composites is found to be dependent on excitation irradiance and it is determined to be -2.9 cmGW at 78 GW cm2, an enhancement of nearly fourfold in comparison with that of pure PbS quantum dots (QDs). The enhancement is attributed to the excitation of surface plasmon by resonant energy transfer between PbS QDs and Au nanoparticles through Auger recombination. © 2008 American Institute of Physics.