The Effect of Oxygen on the Thermoluminescence of Irradiated Polyethylene

Journal Article · Tue Jan 15 04:00:00 EST 1963 · Proceedings of the Royal Society. A. Mathematical, Physical and Engineering Sciences

DOI:https://doi.org/10.1098/rspa.1963.0013· OSTI ID:4757901

Charlesby, A.; Partridge, R. H.

The main thermoluminescence glow curve, the alpha , BETA , gamma glow curve, of polyethylene irradiated by gamma rays at 77 °K was found to be greatly affected by molecular oxygen absorbed in the material before irradiation. The oxygen removes the BETA and gamma peaks almost entirely at low irradiation doses and adds another peak, the epsilon peak, at a lower temperature than these to form an alpha , epsilon glow curve. Kinetic studies showed that the epsilon peak has a higher probability constant at low temperatures than any of the alpha , BETA , gamma peaks but that it shares the same common activation energy. Since the epsilon luminescence cannot be observed at 77 °K it seems that some change, perhaps a structural change, must occur during warming from 77 °K before it can begin to appear. The oxygen effect can be removed by pumping or by a preirradiation followed by preheating. The latter method is shown to remove the oxygen by conversion into peroxide radicals, produced when the oxygen combines with alkyl radicals formed during the preirradiation. The epsilon peak was found to occur only in the presence of oxygen molecules, but not with oxygen in the form of peroxides. Peroxide radical formation was observed by means of the electron spin resonance (e.s.r.) method. E.s.r. measurements also showed that thermoluminescence in polymers was not a direct product of free radical reactions. Various possible thermoluminescence mechanisms are discussed and it is shown that the polyethylene thermoluminescence phenomena can be explained on the basis of a model involving the trapping of electrons followed by their recombination with different types of luminescence centers.

• Research Organization: Royal Military Coll. of Science, Shrivenham, Wiltshire, Eng.
• Sponsoring Organization: USDOE
• NSA Number: NSA-17-012735
• OSTI ID: 4757901
• Journal Information: Proceedings of the Royal Society. A. Mathematical, Physical and Engineering Sciences, Journal Name: Proceedings of the Royal Society. A. Mathematical, Physical and Engineering Sciences Journal Issue: 1345 Vol. 271; ISSN 1364-5021
• Publisher: The Royal Society Publishing
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
DIAGRAMS
ELECTRON SPIN RESONANCE
ELECTRONS
EXCITATION
GAMMA RADIATION
HEATING
IRRADIATION
LATTICES
LOW TEMPERATURE
LUMINESCENCE
MEASURED VALUES
OXIDES
OXYGEN
POLYETHYLENES
POLYMERS
PUMPS
REACTION KINETICS
RESONANCE
SPIN
THERMODYNAMICS