RADICAL-MATRIX INTERACTIONS IN LOW TEMPERATURE GLASSES: PHOTO-REVERSIBILITY,
Abstract
The near UV irradiation of ether and/or ethanol glasses at low temperatures (100 = 25K) leads to the formation of trapped ethyl radicals via an excited impurity-solvent interaction. The radicals were observed by electron para magnetic resonance spectroscopy (EPR), both during the irradiation and during the post irradiation period. The EPR spectral line shapes of the ethyl radicals changed as a function of time after light extinction and also of temperature during irradiation. Qualitative kinetics of the spectral changes were examined in some detail. In the absence of dissolved oxygen the spectral line shape changes are reversible upon re-irradiation; in the presence of oxygen the ethyl radical is irreversibly converted into the RO2 radical at temperatures where the oxygen can appreciably diffuse. The orgins of the spectral changes are discussed in terms of hindered rotational motions and localized phase changes, as well as the postulation of a possible charge transfer complex formation. Photo-reversibility is assumed tto occur via radiationless transitions involving excited states of the impurities. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1964
- Accession Number
- AD0606057
Entities
People
- H. S. Judeikis
- S. Siegel
Organizations
- The Aerospace Corporation