title: Two-photon absorption and degenerate four-wave mixing studies of sulfide semiconductor nanoparticles in polymeric solutions.
abstract: The two-photon absorption coefficients (beta) and the third-order nonlinear susceptibilities (chi(3)) of several semiconductor nanoparticles (CdS, Cd(x)Ag(1-x)S, and core-shell CdS/Ag2S) that are confined and stabilized by random and block ionomers have been measured by nonlinear transmission and degenerate four-wave mixing techniques using 21 picosecond laser pulses at near-infrared spectral region. The imaginary part of the third-order nonlinear susceptibility that is related to the two-photon absorption coefficient was then calculated. The absorptive nonlinearity of the nanoparticles (2 approximately 9 nm) was found to be dependent on the particle size, composition and wavelength, i.e., larger CdS particles exhibit higher two-photon absorption coefficients and the presence of Ag improves two-photon absorption of CdS nanoparticles. The obtained two-photon absorption coefficients of nanoparticles corrected for their volume fraction in solution are significantly greater that those of corresponding bulk semiconductors.
authors.affiliation: Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32603, USA.
authors.forename: Wenling
authors.initials: W
authors.lastname: Jia
authors.forename: Fengqi
authors.initials: F
authors.lastname: Guo
authors.forename: Elliot P
authors.initials: EP
authors.lastname: Douglas
authors.forename: Wenfang
authors.initials: W
authors.lastname: Sun