title: Fabrication and notable optical nonlinearities of ultrathin composite films derived from water-soluble Keggin-type polyoxometalates and water-insoluble phthalocyanine.
abstract: Composite films with the general formula (POM/CuTAPc)nderived from water-soluble Keggin-type polyoxometalates (POMs = H5PMo10V2O40, H4SiW12O40, H3PMo12O40and H3PW12O40) and water-insoluble 4,9,16,23-copper tetraaminophthalocyanine (denoted CuTAPc) are successfully fabricated by a layer-by-layer self-assembly technique and systematically characterized. The structure of the polyoxometalate anions in the multilayers is kept intact; the deposition amounts of POM and CuTAPc remain constant in every adsorption cycle of the composite film assembly process. The nonlinear optical properties of the composite films were studied by a Z-scan technique at a wavelength of 532 nm and a pulse width of 7 ns. The results not only show that the composite films exhibit notable optical nonlinear self-defocusing behavior and a saturated absorption effect with the nonlinear optical absorption co-efficient β, refractive index n2, and third-order NLO susceptibility χ(3)of the films increasing with the increase in number of layers of the films, but also reveal importantly that the discrepancy of LUMO levels between CuTAPc and POMs is proportional to their third-order NLO response.
authors: State Key Laboratory of Chemical Resource Engineering, Institute of Science, Beijing University of Chemical Technology, Beijing 100029, P. R. China. zhouys@mail.buct.edu.cn ljzhang@mail.buct.edu.cn.
authors: Farooq Khurum
authors: FK
authors: Shehzad
authors: Ningning
authors: N
authors: Qu
authors: Yunshan
authors: Y
authors: Zhou
authors: Lijuan
authors: L
authors: Zhang
authors: Huanyao
authors: H
authors: Ji
authors: Zonghai
authors: Z
authors: Shi
authors: Jiaqi
authors: J
authors: Li
authors: Sadaf Ul
authors: SU
authors: Hassan
mesh_terms: D003300:Copper / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry*; D054833:Isoindoles; D008958:Models, Molecular; D017711:Nonlinear Dynamics; D055620:Optical Phenomena; D012995:Solubility; D017973:Tungsten Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry*; D000099294:Polyoxometalates
chemical_list: D003300:Copper; D007211:Indoles; D054833:Isoindoles; D017973:Tungsten Compounds; D014867:Water; C102296:polyoxometalate I; D000099294:Polyoxometalates; C013647:phthalocyanine