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Titolo:
Role of dipole moment of solvents in formation and stabilization of the TICT states in Coumarin 445 under nitrogen laser excitation
Autore:
Vijila, C; Ramalingam, A; Palanisamy, PK; Masilamani, V;
Indirizzi:
Anna Univ, Dept Phys, Ctr Laser Technol, Chennai 600025, India Anna Univ Chennai India 600025 Ctr Laser Technol, Chennai 600025, India
Titolo Testata:
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
fascicolo: 3, volume: 57, anno: 2001,
pagine: 491 - 497
SICI:
1386-1425(20010301)57:3<491:RODMOS>2.0.ZU;2-L
Fonte:
ISI
Lingua:
ENG
Soggetto:
PICOSECOND DYNAMICS; DYE; CONFORMATIONS; FLUORESCENCE; EMISSION;
Keywords:
coumarin; dipole moment; ASE; TICT state; gain; absorption and fluorescence;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
11
Recensione:
Indirizzi per estratti:
Indirizzo: Ramalingam, A Anna Univ, Dept Phys, Ctr Laser Technol, Chennai 600025, India Anna Univ Chennai India 600025 hnol, Chennai 600025, India
Citazione:
C. Vijila et al., "Role of dipole moment of solvents in formation and stabilization of the TICT states in Coumarin 445 under nitrogen laser excitation", SPECT ACT A, 57(3), 2001, pp. 491-497

Abstract

In this paper we report the observation of dual Amplified Spontaneous Emission (ASE) from solutions of 7-ethylamino-4-methyl coumarin dye (Coumarin 445) in certain solvents such as n-butyl acetate, dioxane etc. when pumped by high power nitrogen laser. The two ASE bands appear to be from two different excited species (ICT and TICT conformation) one of which is the precursor of the other. The spectral characteristics of dye Coumarin 445 depend upon the solvent environment. The TICT coumarin photoisomers, which form exciplexes with the solvent molecules, have enough gain to produce amplified spontaneous emission even when there is apparently no detectable fluorescence. The behaviour of this dye in the excited state is studied by measuring the small signal gain and variation of the gain slope with temperature in different solvents. It is observed that polarity of the solvent plays a more dominant role in formation and stabilization of TICT states. (C) 2001 Elsevier Science B.V. All rights reserved.

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Documento generato il 05/04/20 alle ore 11:53:27