Influence of blue valence absorption band on nonlinear absorption in dysprosium bisphthalocyanine studied by open aperture z-scan

Study of the optical limiting (OL) effect in a THF solution of bis(2,3,9,10,16,17,23,24-octabutylphthalocyaninato) dysprosium(III) (BuPc2Dy) by the open aperture z-scan technique with 350 ps laser pulses at 532 nm is presented. The presence of the blue valence (BV) band in UV-Vis absorption spectra of bisphthalocyanines (bisPcs) adds complexity to the nonlinear absorption behavior. Luminescence measurements showed that two channels of excitation exist for BuPc2Dy when illuminating at 532 nm. We suggest a new theoretical model which describes the interaction of a bisPc with an intense laser pulse at 532 nm. Excited state lifetimes and the Q band quantum yield were also determined.