Title

Efficient Two-Photon Absorbing Acceptor-pi-Acceptor Polymethine Dyes

Authors

Authors

L. A. Padilha; S. Webster; O. V. Przhonska; H. H. Hu; D. Peceli; T. R. Ensley; M. V. Bondar; A. O. Gerasov; Y. P. Kovtun; M. P. Shandura; A. D. Kachkovski; D. J. Hagan;E. W. Van Stryland

Comments

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Abbreviated Journal Title

J. Phys. Chem. A

Keywords

EXCITED-STATE ABSORPTION; CROSS-SECTIONS; OPTICAL-PROPERTIES; NONLINEAR; OPTICS; MOLECULES; SQUARAINE; TRANSITIONS; DERIVATIVES; EXCITATION; DIPOLAR; Chemistry, Physical; Physics, Atomic, Molecular & Chemical

Abstract

We present an experimental and theoretical investigation of the linear and nonlinear optical properties of a series of acceptor-pi-acceptor symmetrical anionic polymethine dyes with diethylamino-coumarin-dioxaborine terminal groups and different conjugation lengths. Two-photon absorption (2PA) cross sections (delta(2PA)) are enhanced with an increase of pi-conjugation length in the investigated series of dyes. 2PA spectra for all dyes consist of two well-separated bands. The first band, located within the telecommunications window, occurs upon two-photon excitation into the vibrational levels of the main S(0) -> S(1) transition, reaching a large delta(2PA) = 2200 GM (1 GM = 1 x 10(-50) cm(4) s/photon) at 1600 nm for the longest conjugated dye. The position of the second, and strongest, 2PA band for all anionic molecules corresponds to the second-excited final state, which is confirmed by quantum-chemical calculations and excitation anisotropy measurements. Large delta(2PA) values up to 17 000 GM at 1100 nm are explained by the combination of the large ground- and excited-state transition dipole moments. The three shortest dyes show good photochemical stability and surprisingly large fluorescence quantum yields of approximate to 0.90, approximate to 0.66, and approximate to 0.18 at the red to near-IR region of approximate to 640, approximate to 730, and approximate to 840 nm, respectively. The excited-state absorption spectra for all samples are also studied and exhibit intense bands throughout the visible wavelength region with peak cross section close to 5 x 10(-16) cm(2) with a corresponding red shift with increasing conjugation lengths.

Journal Title

Journal of Physical Chemistry A

Volume

114

Issue/Number

23

Publication Date

1-1-2010

Document Type

Article

Language

English

First Page

6493

Last Page

6501

WOS Identifier

WOS:000278480200006

ISSN

1089-5639

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