Comparison of nonlinear absorption in three similar dyes: Polymethine, squaraine and tetraone

    Authors

    S. Webster; J. Fu; L. A. Padilha; O. V. Przhonska; D. J. Hagan; E. W. Van Stryland; M. V. Bondar; Y. L. Slominsky;A. D. Kachkovski

    Comments

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    Abbreviated Journal Title

    Chem. Phys.

    Keywords

    polymethine; squaraine; tetraone; two-photon absorption; excited-state; absorption; cyanine; EXCITED-STATE ABSORPTION; 2-PHOTON ABSORPTION; SQUARYLIUM MOLECULES; CROSS-SECTIONS; SINGLE-BEAM; ANISOTROPY; Chemistry, Physical; Physics, Atomic, Molecular & Chemical

    Abstract

    We performed a detailed experimental investigation and quantum-chemical analysis of two-photon absorption (2PA) spectra of symmetrical cationic polymethine and neutral squaraine and tetraone dyes having nearly identical terminal groups and similar conjugation length. Squaraine and tetraone structures differ from polymethines in that their conjugated backbone includes an electron accepting bridge. Frequency degenerate 2PA spectra of these molecules are measured by two-photon fluorescence spectroscopy and the Z-scan technique. Comparing 2PA spectra of polymethine with squaraine and tetraone structures, we find that we can access considerably larger 2PA cross-sections ( > -8000 x 10(-50) cm(4) s/photon) in the squaraine and tetraone molecules due to an increase in the density of final states introduced by the electron accepting bridge in the conjugated chain. We discuss the difference in electronic structure for these molecules and introduce a link between 2PA and excited-state absorption spectra. The results of these experiments combined with agreement of quantum-chemical calculations moves us closer to a predictive capability for the relation between molecular structure and nonlinear optical properties. (c) 2008 Elsevier B.V. All rights reserved.

    Journal Title

    Chemical Physics

    Volume

    348

    Issue/Number

    1-3

    Publication Date

    1-1-2008

    Document Type

    Article

    Language

    English

    First Page

    143

    Last Page

    151

    WOS Identifier

    WOS:000256737200017

    ISSN

    0301-0104

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