Electron spin relaxation in solids-an application to spontaneously occurring radical centre in phenol-formaldehyde resins

An outline of electron spin-relaxation is briefly presented with mechanisms and processes of spin-lattice relaxation in ionic and amorphous solids. Electron spin resonance (EPR) and pulsed EPR measurements were performed in the temperature range 4-300 K on a radical occurring in a dried resol phenol...

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Bibliographic Details
Published in:IEEE transactions on dielectrics and electrical insulation 2002-04, Vol.9 (2), p.316-322
Main Authors: Hoffmann, S.K., Hilczer, W., Hoffmann, B.
Format: Article
Language:English
Subjects:
Amorphous materials
Computer simulation
Couplings
Electron spin
Electrons
Ethers
Heating
Molecular dynamics
Paramagnetic resonance
Performance evaluation
Polymers
Pulse measurements
Radicals
Resins
Solids
Spin-lattice relaxation
Temperature distribution
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Summary:An outline of electron spin-relaxation is briefly presented with mechanisms and processes of spin-lattice relaxation in ionic and amorphous solids. Electron spin resonance (EPR) and pulsed EPR measurements were performed in the temperature range 4-300 K on a radical occurring in a dried resol phenol-formaldehyde resin. The radical appears in a small concentration of about 1/spl times/10/sup 16/ radicals/g in 30/spl deg/C dried samples and the number of the radicals increases continuously with time up to 2/spl times/10/sup 17/ radicals/g after 100 days. Computer simulations of the EPR spectrum show that breaking of the dimethylene ether linkage probably forms the radical during synthesis reactions. Electron spin-lattice relaxation rate increases relatively slowly on heating and at
ISSN:1070-9878
1558-4135
DOI:10.1109/94.993750