文摘
The linear and nonlinear optical properties of the heteroaromatic push-pull-push two-photon absorbing dyeN-methyl-2,5-bis[1-(N-methylpyrid-4-yl)ethen-2-yl]-pyrrole ditriflate (PEPEP) are reported. The determinationof the two-photon absorption (TPA) cross-section spectrum has been performed with different techniques:femtosecond TPA-white light continuum probe experiments, two-photon-induced fluorescence, and openaperture Z-scan measurements using both nanosecond and femtosecond laser pulses. The measured TPAcross sections and their wavelength dispersion show a marked dependence on the parameters of the laserpulses and on the measurement technique employed. These properties are discussed in terms of the differentmicroscopic mechanisms that can contribute to the multiphoton absorption processes, with different weightdepending on the measurement conditions and on the photophysical parameters of the dye.