Regensburg 2007 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 1: Supramolecular Aggregates

CPP 1.3: Talk

Monday, March 26, 2007, 10:15–10:30, H37

The absorption spectrum of organic dye aggregates — •Alexander Eisfeld and John Briggs — Theoretische Quantendynamik, Universität Freiburg, Hermann-Herder-Str. 3, D-79104 Freiburg, Germany

Certain molecular aggregates consisting of organic dyes are remarkable in exhibiting an intense and very narrow absorption peak, known as a J-band [1], which is red-shifted away from the region of monomer absorption. Apart from those dyes showing the J-band on aggregation, there are also dyes where the absorption maximum is shifted to higher energies. The width of the resulting absorption band (called an H-band) is comparable to that of the monomeric dyes and shows a complicated vibrational structure.

Following our analysis of the J-band [2,3] spectra of polymer aggregates using the CES approximation, a theory that includes vibrations explicitly, we show that the same approximation can account for measured H-band spectra. Using simple analytical forms of the monomer spectrum the origin of the widely-different shapes of H- and J-bands is explained within the CES approximation [4].

[1] T. Kobayashi, J-Aggregates. World Scientific, 1996

[2] A. Eisfeld, J. S. Briggs, Chem. Phys. 281, 61

[3] A. Eisfeld, J. S. Briggs, Phys. Rev. Lett. 96, 113003

[4] A. Eisfeld, J. S. Briggs, Chem. Phys. 324, 376