Photophysics of Xanthene Dyes at High Concentrations in Solid Environments: Charge Transfer Assisted Triplet Formation

The photophysical behavior of two xanthene dyes, Eosin Y and Phloxine B, included in microcrystalline cellulose particles is studied in a wide concentration range, with emphasis on the effect of dye concentration on fluorescence and triplet quantum yields. Absolute fluorescence quantum yields in the...

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Autores principales: Litman, Yair E., Rodríguez, Hernán Bernardo, Braslavsky, Silvia E, San Román, Enrique
Formato: Articulo Preprint
Lenguaje:Inglés
Publicado: 2018
Materias:
Química
Física
Xanthene dyes
Microcrystalline cellulose
Fluorescence
Triplet state
Charge-transfer
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/125590
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-125590
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Química
Física
Xanthene dyes
Microcrystalline cellulose
Fluorescence
Triplet state
Charge-transfer
spellingShingle Química
Física
Xanthene dyes
Microcrystalline cellulose
Fluorescence
Triplet state
Charge-transfer
Litman, Yair E.
Rodríguez, Hernán Bernardo
Braslavsky, Silvia E
San Román, Enrique
Photophysics of Xanthene Dyes at High Concentrations in Solid Environments: Charge Transfer Assisted Triplet Formation
topic_facet Química
Física
Xanthene dyes
Microcrystalline cellulose
Fluorescence
Triplet state
Charge-transfer
description The photophysical behavior of two xanthene dyes, Eosin Y and Phloxine B, included in microcrystalline cellulose particles is studied in a wide concentration range, with emphasis on the effect of dye concentration on fluorescence and triplet quantum yields. Absolute fluorescence quantum yields in the solid-state were determined by means of diffuse reflectance and steady-state fluorescence measurements, whereas absolute triplet quantum yields were obtained by laser-induced optoacoustic spectroscopy and their dependence on dye concentration was confirmed by diffuse reflectance laser flash photolysis and time-resolved phosphorescence measurements. When both quantum yields are corrected for reabsorption and reemission of radiation, ΦF values decrease strongly on increasing dye concentration, while a less pronounced decay is observed for ΦT . Fluorescence concentration quenching is attributed to the formation of dye aggregates or virtual traps resulting from molecular crowding. Dimeric traps are however able to generate triplet states. A mechanism based on the intermediacy of charge-transfer states is proposed and discussed. Calculation of parameters for photoinduced electron transfer between dye molecules within the traps evidences the feasibility of the proposed mechanism. Results demonstrate that photoactive energy traps, capable of yielding dye triplet states, can be formed even in highly-concentrated systems with random dye distributions.
format Articulo
Preprint
author Litman, Yair E.
Rodríguez, Hernán Bernardo
Braslavsky, Silvia E
San Román, Enrique
author_facet Litman, Yair E.
Rodríguez, Hernán Bernardo
Braslavsky, Silvia E
San Román, Enrique
author_sort Litman, Yair E.
title Photophysics of Xanthene Dyes at High Concentrations in Solid Environments: Charge Transfer Assisted Triplet Formation
title_short Photophysics of Xanthene Dyes at High Concentrations in Solid Environments: Charge Transfer Assisted Triplet Formation
title_full Photophysics of Xanthene Dyes at High Concentrations in Solid Environments: Charge Transfer Assisted Triplet Formation
title_fullStr Photophysics of Xanthene Dyes at High Concentrations in Solid Environments: Charge Transfer Assisted Triplet Formation
title_full_unstemmed Photophysics of Xanthene Dyes at High Concentrations in Solid Environments: Charge Transfer Assisted Triplet Formation
title_sort photophysics of xanthene dyes at high concentrations in solid environments: charge transfer assisted triplet formation
publishDate 2018
url http://sedici.unlp.edu.ar/handle/10915/125590
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