Laser Flash Photolysis of Benzophenone in Polymer Films

With a nanosecond laser we studied flash photolysis of benzophenone (BP) dissolved in four different polymer films. We measured kinetics of decay of a triplet state of benzophenone 3BP as well as kinetics of decay of benzophenone ketyl free radicals BPH•. Polymer matrices have plenty of reactive C–H...

Full description

Saved in:
Bibliographic Details
Published in:The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2011-10, Vol.115 (40), p.10996-11000
Main Authors: Levin, Peter P, Khudyakov, Igor V
Format: Article
Language:English
Subjects:
A: Kinetics, Spectroscopy
Benzophenones - chemistry
Decomposition
Flash photolysis
Free radicals
Hardness
Kinetics
Lasers
Membranes, Artificial
Photolysis
Polymeric films
Polymers - chemistry
Radicals
Reaction kinetics
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:With a nanosecond laser we studied flash photolysis of benzophenone (BP) dissolved in four different polymer films. We measured kinetics of decay of a triplet state of benzophenone 3BP as well as kinetics of decay of benzophenone ketyl free radicals BPH•. Polymer matrices have plenty of reactive C–H bonds, and the hydrogen abstraction by 3BP leads to a formation of geminate pair which either recombines into molecular products or dissociates. Decay kinetics of 3BP is well described by dispersive kinetics and in particular by the kinetic law suggested in Albery W. J. ; et al. J. Am. Chem. Soc. 1985, 107, 1854 . We observed a broader distribution of rate constants in hard films. It was observed that the decay kinetics of transients radicals in the “hard” polymers is quite satisfactory described by the same law for dispersive kinetics. Kinetics of radicals decay in “soft” polymers is satisfactorily described as a diffusion- enhanced reaction. Effect of a hardness of polymer matrix on the measured kinetic parameters is discussed.
ISSN:1089-5639
1520-5215
DOI:10.1021/jp2072183