Enhanced two photon absorption cross section and optical nonlinearity of a quasi-octupolar molecule

• The two photon absorption cross section of DPATSP and its N-methyl derivative have been estimated using Z scan technique.
• Nonlinear refraction and the TPA cross section (σ2) increases by increasing the acceptor strength in quazi-octupolar molecules.
• The Z-scan technique is shown to have a clear advantage over the TPIF method for TPA estimation of weakly fluorescent samples.

Two photon absorption (2PA) cross sections of two quasi-octupolar molecules (E,E,E)-2,4,6-tris [2-(4-N,N-diphenylaminophenyl)vinyl]pyridine (DPATSP) and (2,4,6-tris((E)-4-(diphenylamino)styryl)-1-methylpyridine-1-ium iodide, DPATSP-Me) have been estimated. It has been found that by introducing the pyridinium ion, the 2PA cross section of DPATSP-Me increases with respect to the parent molecule, DPATSP. Z-scan experiments on the two samples reveal that DPATSP-Me is a better candidate for optical limiting applications.

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