Large Nonlinear Absorption in Coated Ag2S/CdS Nanoparticles by Inverse Microemulsion

A modified inverse microemulsion technique was used to synthesize coated Ag 2 S/CdS nanocomposites of ∼10 nm in diameter. Their nonlinear absorption was observed with picosecond and nanosecond laser radiation of 532-nm wavelength. The nonlinear absorption in the Ag 2 S/CdS nanocomposites was enhanced, in comparison with the CdS nanoparticles, due to free-carrier absorption. In addition, the relaxation times of photoexcited free carriers in the Ag 2 S/CdS nanocomposites were also determined to be a few nanoseconds.