The detection and enhancement of ultra weak chemiluminescence from autoxidation systems
The detection and enhancement of ultra weak chemiluminescence from autoxidation systems
An investigation has been made into the qualitative and quantitative uses of ultra weak chemiluminescence(CL) arising from organic oxidations. Autoxidation of the typical lipid model, methyl linoleate, indicates that there are a minimum of two distinct emitting species in this system and probably many more. No clear identification of the primary excited species could be made. Quantitative measurements on an autoxidising-mixture of azoisobutyronitrile(AIBN) and ethyl benzene(EB) can be made by the use of computer simulation techniques, allowing calculation of the termination rate constant between 2-cyanopropyl peroxy radicals and ED peroxy radicals. The derived value was k = 1.9 x 107l.mol 1s-1, close to the value known for two ED peroxy radicals, thus indicating that the absence of an abstractable hydrogen atom in the tertiary peroxy radical is of little importance in this reaction. The use of anthracene derivatives as intensifiers of CL is described and the photophysics of a number of conventional and novel intensifiers has been investigated. The work was carried out in both solution and gas phases and these showed contrasting behaviour: Temperature effects on fluorescence lifetimes in solution show that the predominant non radiative process is an intersystem crossing with an activation energy of '1000cm 1 and a pre-exponential factor of -1095 1. In the gas phase, the corresponding values were 4000cm 1 and 1013s 1 implying an internal conversion. Refractive index effects on the singlet state radiative rate constant for these molecules have also been measured and an n' relation well established.
University of Southampton
1982
Lampert, Roger Andrew
(1982)
The detection and enhancement of ultra weak chemiluminescence from autoxidation systems.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
An investigation has been made into the qualitative and quantitative uses of ultra weak chemiluminescence(CL) arising from organic oxidations. Autoxidation of the typical lipid model, methyl linoleate, indicates that there are a minimum of two distinct emitting species in this system and probably many more. No clear identification of the primary excited species could be made. Quantitative measurements on an autoxidising-mixture of azoisobutyronitrile(AIBN) and ethyl benzene(EB) can be made by the use of computer simulation techniques, allowing calculation of the termination rate constant between 2-cyanopropyl peroxy radicals and ED peroxy radicals. The derived value was k = 1.9 x 107l.mol 1s-1, close to the value known for two ED peroxy radicals, thus indicating that the absence of an abstractable hydrogen atom in the tertiary peroxy radical is of little importance in this reaction. The use of anthracene derivatives as intensifiers of CL is described and the photophysics of a number of conventional and novel intensifiers has been investigated. The work was carried out in both solution and gas phases and these showed contrasting behaviour: Temperature effects on fluorescence lifetimes in solution show that the predominant non radiative process is an intersystem crossing with an activation energy of '1000cm 1 and a pre-exponential factor of -1095 1. In the gas phase, the corresponding values were 4000cm 1 and 1013s 1 implying an internal conversion. Refractive index effects on the singlet state radiative rate constant for these molecules have also been measured and an n' relation well established.
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Published date: 1982
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Local EPrints ID: 460229
URI: http://eprints.soton.ac.uk/id/eprint/460229
PURE UUID: ff858990-fa4e-4d68-9b70-7d72c1b3ebeb
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Date deposited: 04 Jul 2022 18:13
Last modified: 04 Jul 2022 18:13
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Author:
Roger Andrew Lampert
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