Effect of Concentration on the Formation of Rose Bengal Triplet State on Microcrystalline Cellulose: A Combined Laser-Induced Optoacoustic Spectroscopy, Diffuse Reflectance Flash Photolysis, and Luminescence Study

2014 ◽  
Vol 118 (45) ◽  
pp. 10531-10537 ◽  
Author(s):  
Yair Litman ◽  
Matthew G. Voss ◽  
Hernán B. Rodríguez ◽  
Enrique San Román
Keyword(s):  
Triplet State ◽  
Microcrystalline Cellulose ◽  
Rose Bengal ◽  
Diffuse Reflectance ◽  
Flash Photolysis ◽  
Luminescence Study ◽  
Optoacoustic Spectroscopy

scholarly journals Surface photochemistry: Photodegradation study of pyrene adsorbed onto microcrystalline cellulose and silica

2004 ◽  
Vol 6 (4) ◽  
pp. 205-213 ◽  
Author(s):  
A. S. Oliveira ◽  
L. F. Vieira Ferreira ◽  
J. P. Da Silva ◽  
J. C. Moreira
Keyword(s):  
Radical Cation ◽  
Microcrystalline Cellulose ◽  
Ground State ◽  
Diffuse Reflectance ◽  
Transient Absorption ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Cation Radical ◽  
Laser Flash ◽  
Time Resolved

Ground-state diffuse reflectance, time resolved laser-induced luminescence, diffuse reflectance laser flash-photolysis transient absorption and chromatographic techniques were used to elucidate the photodegradation processes of pyrene adsorbed onto microcrystalline cellulose and silica. Ground-state diffuse reflectance showed that on both substrates low concentrations display absorption of pyrene monomers. At high concentrations spectral changes attributed to aggregate formation were observed. Laser induced fluorescence showed that pyrene onto microcrystalline cellulose mainly presents fluorescence from monomers, while for silica, excimer-like emission was observed from low surface loadings (≥0.5μmolg−1). Transient absorption and photodegradation studies were performed at concentrations where mainly monomers exist. On silica, pyrene presents transient absorption from its radical cation. On microcrystalline cellulose both radical cation, radical anion and pyrene triplet-triplet absorption were detected. Irradiation followed by chromatographic analysis showed that pyrene decomposes on both substrates. For pyrene on microcrystalline cellulose 1-hydroxypyrene was the main identified photoproduct since in the absence of oxygen further oxidation of 1-hydroxypyrene was very slow. For pyrene on silica photodegradation was very efficient. Almost no 1-hydroxypyrene was detected since in the presence of oxygen it is quickly oxidized to other photooxidation products. On both substrates, pyrene radical cation is the intermediate leading to photoproducts and oxygen it is not involved in its formation.

Effect of Aggregation on Bacteriochlorin a Triplet-state Formation: A Laser Flash Photolysis Study¶

2002 ◽  
Vol 76 (5) ◽  
pp. 480 ◽  
Author(s):  
Xavier Damoiseau ◽  
Francis Tfibel ◽  
Maryse Hoebeke ◽  
Marie-Pierre Fontaine-Aupart
Keyword(s):  
Triplet State ◽  
State Formation ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash

The polymerization of styrene sensitized by molecules in the triplet state II. Kinetics and mechanism

1959 ◽  
Vol 251 (1264) ◽  
pp. 4-26 ◽  
Keyword(s):  
Triplet State ◽  
Aromatic Hydrocarbons ◽  
Flash Photolysis ◽  
Radical Addition ◽  
Photochemical Reactions ◽  
Kinetics And Mechanism ◽  
Qualitative Investigation ◽  
Initiation Mechanism ◽  
Initial Formation ◽  
Mechanism Of The Reaction

The kinetics and mechanism of the reaction between anthracene and styrene have been fully investigated. By means of flash photolysis techniques, it has been confirmed that it is the triplet state of anthracene which sensitizes the polymerization. It has also been shown that both triplet and unexcited singlet anthracene copolymerize with styrene, the former with a zero activation energy. The work has been extended to the polymerizations sensitized by pyrene and chrysene, and to the unsensitized photopolymerization of styrene. It has been shown that in every case an initiation mechanism, involving the initial formation of a triplet-monomer complex, satisfactorily explains the observed results. The copolymerization rates of pyrene and chrysene were undetectable; these results, coupled with those obtained for the copolymerization of anthracene with styrene, are in agreement with the conclusions of Kooyman & Farenhorst, Szwarc, and others, concerning the reactivity of olefinic and aromatic hydrocarbons to radical addition. Finally, a qualitative investigation of the photochemical reactions between the sensitizers, and cumene and 9 .10-dihydroanthracene, has been made.

Quenching Mechanism of Rose Bengal Triplet State Involved in Photosensitization of Oxygen in Ethylene Glycol

2006 ◽  
Vol 110 (5) ◽  
pp. 1735-1739 ◽  
Author(s):  
Okiyasu Shimizu ◽  
Jun Watanabe ◽  
Shizuo Naito ◽  
Yasushi Shibata
Keyword(s):  
Ethylene Glycol ◽  
Triplet State ◽  
Rose Bengal ◽  
Quenching Mechanism
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