title: Non-quadratic-intensity dependence of two-photon absorption induced fluorescence of organic chromophores in solution.
abstract: We have provided a model to interpret the non-quadratic-intensity dependence behavior commonly observed in the two-photon fluorescence (TPF) experiment excited with high laser intensity. The model also provides one with a different technique to measure the two-photon absorption cross section of an organic chromophore in solution. In contrast to the commonly used low intensity technique that depends on the quadratic-intensity law, the present technique is based on the non-quadratic-intensity dependence of two-photon fluorescence. Auxiliary data such as two-photon quantum efficiency and fluorescence collection efficiency, essential in the low intensity method, are not required in the present technique. TPF measurements of Rhodamine B in methanol are carried out to demonstrate the validity of the present method. The method is used to determine the two-photon absorption cross section of a new chromophore attached with tricyano-derivatized furan as the electron acceptor. The two-photon absorption cross section measured using this method is also compared with that using a conventional transmission technique.
authors.affiliation: Center of Organic Materials for Advanced Technology and Department of Physics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan. jimwang@mail.nysu.edu.tw
authors.forename: C H
authors.initials: CH
authors.lastname: Wang
authors.forename: Oliver Y-H
authors.initials: OY
authors.lastname: Tai
authors.forename: Yuxiao
authors.initials: Y
authors.lastname: Wang
authors.forename: Tsung-Hsiu
authors.initials: TH
authors.lastname: Tsai
authors.forename: Nein-Chen
authors.initials: NC
authors.lastname: Chang