Faraday-Tyndall effect of gold colloids

We measured the divergence angles of a CW laser beam passing through gold colloids with different concentrations to quantitatively characterize Faraday-Tyndall effect. Our results show that the divergence angles of 532-nm and 785-nm CW laser beams through gold nanoparticles (GNPs) colloid are increased as the concentration of GNPs increases. The increased divergence angle of GNP at 532 nm is more significant than that at 785 nm, because the surface plasmon resonance of GNP is at 549 nm. Moreover, the effects of different-sized GNPs will be studied.