title: Experimental and theoretical investigation of the first-order hyperpolarizability of octupolar merocyanine dyes.
abstract: Hyper-Rayleigh scattering experiments and quantum chemical calculations are combined to investigate the second-order nonlinear optical responses of a series of three-arm merocyanine derivatives. They exhibit an octupolar hyperpolarizability response with lower amplitude than crystal violet due to a lower extent of the photoinduced charge transfer and reduced bond length alternation. Strong effects on the second-order optical response measured close to the two-photon absorption level are clearly evidenced; for example, the effective measured polarization ratio deviates below the ideal octupolar value of 3/2 even at very low excitation power. These effects are attributed to two-photon absorption resonance, which we believe modifies dynamically the population of the ground state versus that of the excited state.
authors: Institut des Sciences Moléculaires, CNRS UMR5255, Université de Bordeaux, 351 Cours de la Libération, 33405 Talence (France).
authors: Frédéric
authors: F
authors: Castet
authors: Mireille
authors: M
authors: Blanchard-Desce
authors: Frédéric
authors: F
authors: Adamietz
authors: Yevgen M
authors: YM
authors: Poronik
authors: Daniel T
authors: DT
authors: Gryko
authors: Vincent
authors: V
authors: Rodriguez
mesh_terms: D008958:Models, Molecular; D017785:Photons; D011744:Pyrimidinones / Q000737:chemistry*; D011789:Quantum Theory
chemical_list: D011744:Pyrimidinones; C003954:merocyanine dye
keywords: dyes/pigments; hyperpolarizability; merocyanines; nonlinear optics; quantum chemistry