ESR studies of irradiated methane and ethane at 4. 2 K and mechanism of pairwise trapping of radicals in irradiated alkanes

Journal Article · Wed Aug 15 04:00:00 EDT 1979 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1002/chin.197950063· OSTI ID:5938560

Toriyama, K; Iwasaki, M; Nunome, K

The spatial distributions of trapped hydrogen atoms and methyl radicals in CH/sub 4/ and CD/sub 4/ irradiated at 4.2 K have been studied by ESR. Most of the hydrogen atoms are trapped within approx.16 A from each parent methyl radical forming distributed radical pairs. This indicates that the thermalization distance of hydrogen atoms produced by 4.2 K radiolysis is < or approx. =16 A in methane. Evidence has been obtained for the formation of a small amount of CH/sub 3/...CH/sub 3/ pairs, which are supposedly formed from hot hydrogen atom reactions. No evidence has been obtained for the formation of a pair of hydrogen atoms. There has been also obtained the experimental evidence that thermal hydrogen atoms unreactive with methane can abstract a hydrogen atom from ethane at 10--20 K. In the light of these results, the following conclusions are deduced: A part of hydrogen atoms produced in radiolysis of alkanes undergo hot abstraction to form very close alkyl radical pairs whereas the rest is thermalized and immobilized at the place close to each parent alkyl radical. The thermalized hydrogen atoms also abstract a hydrogen atom from the surrounding molecules to form distributed alkyl radical pairs, when the matrix molecule is reactive with thermal hydrogen atoms. On the other hand, the hydrogen atoms are mobile at elevated temperatures and the isolated alkyl radicals are mainly formed.

• Research Organization: Government Industrial Research Institute, Nagoya, Hirate, Kita, Nagoya, Japan
• OSTI ID: 5938560
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 71:4; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600* -- Radiation Chemistry
ALKANES
ALKYL RADICALS
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
CRYOGENIC FLUIDS
DECOMPOSITION
DISTRIBUTION
ELECTRON SPIN RESONANCE
ELEMENTS
ETHANE
FLUIDS
HYDROCARBONS
HYDROGEN
ION PAIRS
MAGNETIC RESONANCE
METHANE
METHYL RADICALS
NONMETALS
ORGANIC COMPOUNDS
RADIATION CHEMISTRY
RADIATION EFFECTS
RADICALS
RADIOLYSIS
RESONANCE
SPATIAL DISTRIBUTION
TRAPPING
ULTRALOW TEMPERATURE