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Abbreviated Journal Title

J. Chem. Phys.

Keywords

Density Functional Theory; Light Absorption; Nonlinear Optics; Optical; Properties; Physical Optics; Density-Functional Theory; 2-Photon Absorption; Films; Nanotechnology; Chromophores; Aggregation; Physics; Atomic; Molecular & Chemical

Abstract

The photophysical properties of a symmetric squaryllium dye, namely, 2,4-bis[4-(N,N-dibutylamino)-2-hydroxyphenyl] squaraine (SQ), in its monomer form in acetone solution, have been thoroughly studied by means of one-photon absorption (1PA) and two-photon absorption (2PA), excitation anisotropy, fluorescence emission, fluorescence quantum yield, and excited state absorption. The results show that there is a strong one-photon allowed absorption band in the near IR region associated with intramolecular charge transfer. Higher one-photon allowed and forbidden singlet excited states were also revealed by absorption and excitation anisotropy. A relatively high fluorescence quantum yield (0.44) was measured for this dye. The nonlinear optical characterization of SQ in solution confirms the ability of squaraine dyes to be used as good two-photon absorbers. Additionally, it was found that this dye presents both saturable and reverse saturable absorption effects. Density functional theory calculations of the 1PA and 2PA electronic spectra of SQ were carried out to support the experimental data. A detailed analysis of the symmetry and energy of the orbitals involved in the lowest five electronic transitions is presented and discussed in relation to the behavior observed experimentally.

Journal Title

Journal of Chemical Physics

Volume

130

Issue/Number

21

Publication Date

1-1-2009

Document Type

Article

Language

English

First Page

6

WOS Identifier

WOS:000266674400025

ISSN

0021-9606

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