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Titolo:
Excitons in molecular aggregates of 3,3'-bis-[3-sulfopropyl]-5,5'-dichloro-9 ethylthiacarbocyanine (THIATS): Temperature dependent properties
Autore:
Scheblykin, IG; Sliusarenko, OY; Lepnev, LS; Vitukhnovsky, AG; Van der Auweraer, M;
Indirizzi:
Katholieke Univ Leuven, Lab Mol Dynam & Spect, B-3001 Louvain, Belgium Katholieke Univ Leuven Louvain Belgium B-3001 t, B-3001 Louvain, Belgium RAS, P N Lebedev Res Ctr Phys, P N Lebedev Phys Inst, Moscow 117924, Russia RAS Moscow Russia 117924 s, P N Lebedev Phys Inst, Moscow 117924, Russia
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 20, volume: 105, anno: 2001,
pagine: 4636 - 4646
SICI:
1520-6106(20010524)105:20<4636:EIMAO3>2.0.ZU;2-O
Fonte:
ISI
Lingua:
ENG
Soggetto:
OPTICAL-PROPERTIES; ENERGY-TRANSFER; DYNAMICS; DYE; FLUORESCENCE; PSEUDOISOCYANINE; SPECTROSCOPY; ANNIHILATION; PICOSECOND; DISORDER;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
54
Recensione:
Indirizzi per estratti:
Indirizzo: Van der Auweraer, M Katholieke Univ Leuven, Lab Mol Dynam & Spect, Celestijnenlaan 200 F, B-3001 Louvain, Belgium Katholieke Univ Leuven Celestijnenlaan 200 F Louvain Belgium B-3001
Citazione:
I.G. Scheblykin et al., "Excitons in molecular aggregates of 3,3'-bis-[3-sulfopropyl]-5,5'-dichloro-9 ethylthiacarbocyanine (THIATS): Temperature dependent properties", J PHYS CH B, 105(20), 2001, pp. 4636-4646

Abstract

J-aggregates of the dye THIATS (triethylammonium salt of 3,3 ' -bis-[3-sulfopropyl]-5,5 ' -dichloro-9-ethylthia-carbocyanine) with a two-component Davydov splitting of the exciton band were investigated in the temperature range from 5 to 130 K and at room temperature. A wide set of excitonic and optical characteristics (absorption line broadening, fluorescence line broadening, Stokes shift, coherence length, exciton migration rate, and wavelength dependence of the fluorescence decay time) of the same J-aggregates is presented. The exciton migration rate was found to be the most temperature sensitive property. The temperature dependence of a whole set of exciton properties reveals two critical temperatures: 30 and 70 K. The observed phenomena are described qualitatively as an interplay of static and dynamic disorder effects. At low temperature (T < 20 K) static disorder is the main factor which limits the coherence length and exciton-exciton annihilation rate and determines the absorption width. An intraband, subnanosecond exciton relaxation toward the lower energy states is observed. Below 20 K only a limited number of exciton states of the molecular ensemble are reached by the exciton during downhill relaxation. While the temperature increases from 30 to 70 K, a wider set of states becomes accessible for the exciton during itsrelaxation. The "internal" structure of the exciton band becomes blurred by homogeneous broadening and the coherence length decreases. Very fast exciton wave packet motion occurs over 10(6)-10(7) molecules. At temperatures higher than 80 K, we suggest dynamical processes to play the most important role. The Stokes shift becomes temperature independent. Exciton migration starts to be strongly blocked by scattering on optical phonons. The effective, long distance exciton migration in THIATS J-aggregates as well as peculiarities of the Stokes shift and line broadening temperature dependence allow us to conclude that no exciton self-trapping process occurs at temperatures higher than 20 K.

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Documento generato il 01/06/20 alle ore 02:25:56