NUKLEONIKA 2005, 50(Supplement 2):S51-S54
Marek Danilczuk1,2, Jaros³aw Sad³o1, Anders Lund2, Hirohisa Yamada3, Jacek Michalik1
1 Institute of Nuclear Chemistry and Technology, 16 Dorodna Str., 03-195 Warsaw, Poland
2 Department of Physics and Measurements Technology, Linköping University,
S-581 83 Linköping, Sweden
3 National Institute for Material Science and Technology (AIST),
1-1 Namiki, Tskuba, Ibaraki 305 0044, Japan
Methyl radicals generated by g-irradiation in the proton form of synthetic rho zeolite exposed to CH4
have been investigated by electron paramagnetic resonance (EPR) in the temperature range 110–370 K.
Depending on the methane adsorption temperature two EPR spectra of ·CH3 radicals were
recorded. The isotropic quartet observed after CH4 adsorption at room temperature was assigned to ·CH3
radicals freely rotating in the middle of octagonal prism. After adsorption at 413 K, the isotropic
quartet is overlapped with the second signal characterized with anisotropy of hyperfine splitting and
g-value. It is postulated that anisotropic signal represents the ·CH3 radicals located in
a-cages and strongly interacting with silicaalumina framework. The mechanisms
of radiolytic formation of methyl radicals and the possible stabilization sites are also discussed.