Large molecular third-order optical nonlinearities in polarized carotenoids

    Authors

    S. R. Marder; W. E. Torruellas; M. BlanchardDesce; V. Ricci; G. I. Stegeman; S. Gilmour; J. L. Bredas; J. Li; G. U. Bublitz;S. G. Boxer

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    Abbreviated Journal Title

    Science

    Keywords

    POLARIZABILITIES; SUSCEPTIBILITY; GENERATION; POLYENES; LENGTH; BETA; Multidisciplinary Sciences

    Abstract

    Garito and cc-workers have suggested a mechanism to dramatically increase the second hyperpolarizability, gamma, in linear pi-electron-conjugated molecules. Polarization is introduced that leads to a difference between the dipole moments of the molecule's ground state and excited state. Here a series of carotenoids was examined that had increasing intramolecular charge transfer (ICT) from the polyenic chain to the acceptor moiety in the ground state, and gamma was measured for these compounds as a function of wavelength by third-harmonic generation. The compound with the greatest ICT exhibited a 35-fold enhancement of gamma(max) (the gamma measured at the peak of the three-photon resonance) relative to the symmetric molecule beta-carotene, which itself has one of the largest third-order nonlinearities known. Stark spectroscopic measurements revealed the existence of a large difference dipole moment, Delta mu, between the ground and excited state. Quantum-chemical calculations underline the importance of interactions involving states with large Delta mu.

    Journal Title

    Science

    Volume

    276

    Issue/Number

    5316

    Publication Date

    1-1-1997

    Document Type

    Article

    Language

    English

    First Page

    1233

    Last Page

    1236

    WOS Identifier

    WOS:A1997XA49700035

    ISSN

    0036-8075

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