title: Effective two-photon absorption cross section of heteroaromatic quadrupolar dyes: dependence on measurement technique and laser pulse characteristics.
abstract: The linear and nonlinear optical properties of the heteroaromatic push-pull-push two-photon absorbing dye N-methyl-2,5-bis[1-(N-methylpyrid-4-yl)ethen-2-yl]-pyrrole ditriflate (PEPEP) are reported. The determination of 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 open aperture Z-scan measurements using both nanosecond and femtosecond laser pulses. The measured TPA cross sections and their wavelength dispersion show a marked dependence on the parameters of the laser pulses and on the measurement technique employed. These properties are discussed in terms of the different microscopic mechanisms that can contribute to the multiphoton absorption processes, with different weight depending on the measurement conditions and on the photophysical parameters of the dye.
authors.affiliation: Department of Chemical Science and INSTM, University of Padova, Via Marzolo 1, I-35131 Padova, Italy.
authors.forename: Raffaella
authors.initials: R
authors.lastname: Signorini
authors.forename: Camilla
authors.initials: C
authors.lastname: Ferrante
authors.forename: Danilo
authors.initials: D
authors.lastname: Pedron
authors.forename: Michele
authors.initials: M
authors.lastname: Zerbetto
authors.forename: Elio
authors.initials: E
authors.lastname: Cecchetto
authors.forename: Matteo
authors.initials: M
authors.lastname: Slaviero
authors.forename: Ilaria
authors.initials: I
authors.lastname: Fortunati
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Collini
authors.forename: Renato
authors.initials: R
authors.lastname: Bozio
authors.forename: Alessandro
authors.initials: A
authors.lastname: Abbotto
authors.forename: Luca
authors.initials: L
authors.lastname: Beverina
authors.forename: Giorgio A
authors.initials: GA
authors.lastname: Pagani