Investigation of nonlinear optical properties of protonated mixed (porphyrinato)(phthalocyaninato) rare-earth(III) double-decker complexes by Z-scan technique

Nonlinear optical properties of a series of protonated mixed (porphyrinato)(phthalocyaninato) rare-earth double-decker complexes [(MH)-H-III(TClPP){Pc(alpha-OC4H9)(8)}] (1-6; M = Sm, Eu, Tb, Y, Ho, Lu; TClPP = meso-tetrakis(4-chlorophenyl) porphyrinate; Pc(alpha-OC4H9)(8) = 1,4,8,11,15,18,22,25-octakis(1-butyloxy) phthalocyaninate) in dichloromethane were studied by using Z-scan technique with the fundamental laser emission at 800 nm from a Ti:sapphire femtosecond laser system under different incident laser intensities. All these complexes showed strong reverse saturable absorption related to the excited singlet population in a simple three-energy-level model which was established for the interpretation of the experimental results. Both the linear and effective nonlinear absorption coefficients of these complexes decreased approximately following the ionic radius contraction sequence of the rare-earth(III) cations within these complexes under the same situations. The effective excited-state absorption cross sections were determined as well.