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-octabutylphthaloc-yaninato) 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.