Paramagnetic species in irradiated organic glasses. 2. Formation and decay of tetramethylethylene radical cations and effects of some additives on free-radical yields
ESR study shows that glassy 3-methylpentane (3-MP) with 0.3% tetramethylethylene (TME) ..gamma.. irradiated at 77/sup 0/K yields the monomer radical cations of TME(TME/sup +/), the trapped electrons (e/sub t//sup -/), and the free radicals from 3-MP. Both the TME/sup +/ and the e/sub t//sup -/ are unstable at 77/sup 0/K, and most of them disappear within 1 hr. When 0.2% CO/sub 2/ is added to 0.3% TME-3-MP, TME/sup +/ together with the CO/sub 2//sup -/ formed is stabilized. TME/sup +/ and e/sub t//sup -/ in 0.3% TME-3-methylheptane (3-MHP) are bleachable by light with lambda > 800 nm, while TME/sup +/ and CO/sub 2//sup -/ in 0.3% TME-0.2% CO/sub 2/-3-MPH are stable to photoirradiation with lambda > 800 nm and unstable to light with lambda < 400 nm. These photo- and thermal decays are concluded to be caused by charge recombination with a mobile electron activated from its trapping site. The radical cations of TME dimer complexes (TME/sub 2//sup +/) are formed at TME concentrations higher than 1% and disappear by neutralization with electrons as concluded in the case of TME/sup +/. Optical absorption study shows that a broad band with lambda/sub max/ approx. 860 nm observed in ..gamma..-irradiated 1% CO/sub 2/-3-MP with TME higher than 0.3% is attributed to TME/sub 2//sup +/ and that TME/sup +/ does not give a distinct band at wavelengths longer than 500 nm. The 100-eV yields (G values) of paramagnetic species in 3-MHP glasses with and without additives (CO/sub 2/ and TME) are obtained by ESR methods. Radiolysis of glassy n-butyl chloride and polycrystalline CCl/sub 4/ each containing TME yields TME/sup +/; however, polycrystalline n-heptane containing TME and CO/sub 2/ or n-butyl chloride does not give TME/sup +/. It is observed that ESR signals from TME/sup +/ in the CCl/sub 4/ matrix are enhanced by photoirradiation with lambda > 800 nm or by warming. 22 figures, 2 tables.
- Research Organization:
- Hiroshima Univ., Japan
- OSTI ID:
- 6479466
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 83:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALKANES
RADIOLYSIS
ALKENES
CARBON DIOXIDE
CARBON TETRACHLORIDE
CHLORINATED ALIPHATIC HYDROCARBONS
ELECTRONS
CHEMICAL REACTION YIELD
RADICALS
ABSORPTION SPECTRA
ADDITIVES
CHEMICAL PREPARATION
COMPARATIVE EVALUATIONS
DIMERS
ELECTRON SPIN RESONANCE
GAMMA RADIATION
GLASS
IONIZATION POTENTIAL
LOW TEMPERATURE
MONOMERS
STABILITY
TEMPERATURE DEPENDENCE
TIME DEPENDENCE
TRAPPING
VISIBLE RADIATION
WAVELENGTHS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
DECOMPOSITION
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
FERMIONS
HALOGENATED ALIPHATIC HYDROCARBONS
HYDROCARBONS
IONIZING RADIATIONS
LEPTONS
MAGNETIC RESONANCE
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIATIONS
RESONANCE
SPECTRA
SYNTHESIS
YIELDS
400600* - Radiation Chemistry