Published November 29, 1996
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Femtosecond study of laser dyes soluble in water: coumarins
Creators
- Cassara, Laurence
- Universite Paris 6 (France)
- Commissariat a l'energie atomique et aux energies alternatives - CEA-Saclay, Departement de Recherche sur l'Etat Condense, des Atomes et des Molecules - D.R.E.C.A.M., Service de Chimie Moleculaire - S.C.M., Laboratoire de Phophysique et Photochimie - Unite de Recherche Associee CEA/CNRS URA 331 (France)
Description
Coumarins build up one of the great families of laser dyes, and this research thesis addresses the study of four water-soluble coumarins (ATC, DMATC, DATC, and CHOS) which are analogue to conventional coumarins (C120, C311, C1, and C102). These molecules are made water-soluble by substitution of the methyl group in position 4 by a polyether group. Mechanisms of deactivation are studied by means of time-resolved fluorescence and transient adsorption methods which allow the reaction dynamics of coumarins after light excitation to be studied. Several time scales, from femto- to nano-second, have been reached and allowed various processes to be studied: relaxation, solvation dynamics, solute orientation diffusion, process of deactivation of radiative and non-radiative relaxation in various solvents
Abstract (French)
Les coumarines constituent l'une des grandes familles de colorants laser. Les rendements quantiques et durees de vie de fluorescence des 7-aminocoumarines dependent du solvant mais egalement du degre d'alkylation du groupement amino. Dans l'eau, solvant extremement protique, le rendement et la duree de vie de fluorescence de la 7-diethylamino-4-methyl-coumarine (C1) diminuent d'un facteur dix montrant l'ouverture d'une voie de desactivation non radiative du premier etat singulet excite. Les proprietes photophysiques des coumarines C1 et C120 (7-amino-4-methyl-coumarine) et de leurs analogues hydrosolubles DATC et ATC ont ete etudiees et interpretees en s'appuyant sur le modele de Taft et Kamlet. Cette etude permet de preciser l'influence de la polarite et du caractere donneur ou accepteur de liaisons hydrogene du solvant sur le deplacement de leurs spectres d'absorption et de fluorescence UV-visible stationnaires. L'evolution temporelle des spectres de fluorescence des coumarines C1 et DATC a l'echelle subpicoseconde a ete etudiee par la methode pompe-sonde basee sur la generation de la somme de frequences dans un cristal optique non lineaire. Le deplacement spectral aux temps courts depend du solvant mais egalement du solute. Il faut donc tenir compte de la nature du solute pourtant absent des modeles classiques du continuum dielectrique. La diffusion rotationnelle de la coumarine C1 est modelisee en assimilant le solute a un ellipsoide oblate dans des conditions aux limites de type 'stick' ou 'slip' selon le solvant. Dans les alcools lineaires, les molecules de solvant 'collent' au solute ('stick') et dans les autres solvants, au contraire, elles 'glissent' ('slip'). Les constantes de temps courtes des declins biexponentiels d'anisotropie des coumarines C1 (20 ps) et DATC (60 ps) ne peuvent pas etre expliquees dans le cadre de la theorie de Debye-Stokes-Einstein. (auteur)Files
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Additional details
Additional titles
- Original title (French)
- Etude femtoseconde de colorants laser solubles dans l'eau: les coumarines
Identifiers
Publishing Information
- Imprint Pagination
- 260 p.
- Report number
- FRCEA-TH--7793
INIS
- Country of Publication
- France
- Country of Input or Organization
- France
- INIS RN
- 47126551
- Subject category
- S37: INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY;
- Resource subtype / Literary indicator
- Thesis
- Descriptors DEI
- CHARGE TRANSPORT; CHEMICAL REACTIONS; COUMARIN; DEACTIVATION; DIFFRACTION METHODS; FLUORESCENCE; FLUORESCENCE SPECTROSCOPY; FREQUENCY MIXING; LASER RADIATION; LASER SPECTROSCOPY; PHOTOCHEMISTRY; QUANTITATIVE CHEMICAL ANALYSIS; RELAXATION; ROTATIONAL STATES; SOLVATION; STRUCTURAL CHEMICAL ANALYSIS
- Descriptors DEC
- ANTICOAGULANTS; CHEMICAL ANALYSIS; CHEMISTRY; DRUGS; ELECTROMAGNETIC RADIATION; EMISSION; EMISSION SPECTROSCOPY; ENERGY LEVELS; ESTERS; EXCITED STATES; HEMATOLOGIC AGENTS; HETEROCYCLIC COMPOUNDS; HETEROCYCLIC OXYGEN COMPOUNDS; LACTONES; LUMINESCENCE; ORGANIC COMPOUNDS; ORGANIC OXYGEN COMPOUNDS; PHOTON EMISSION; PYRANS; RADIATIONS; SPECTROSCOPY
Optional Information
- Notes
- 374 refs.; Available from the INIS Liaison Officer for France, see the 'INIS contacts' section of the INIS website for current contact and E-mail addresses: http://www.iaea.org/inis/Contacts/