ESR Evidence on Trapped Electrons and ``CO2−'' in γ‐Irradiated 3‐Methylpentane

The singlet ESR signal of γ‐irradiated 3‐methylpentane (3‐MP) glass [K. Tsuji, H. Yoshida, and K. Hayashi, J. Chem. Phys. 46, 810 (1967)], which is attributable to physically trapped electrons, and the singlet and doublet resulting from reaction of electrons with CO2 [P. M. Johnson and A. C. Albrecht, J. Chem. Phys. 44, 1845 (1966)] in 3‐MP glass have been examined further. Immediately after production by a 1019‐eV g−1, 5‐min γ dose, the electron line decays with an apparent half‐life of less than 20 min. It is readily removed by illumination at 13 500 A. ESR saturation is significant at 10−3 mW and prevents detection of the signal at powers above ∼1 mW. The ESR g value and the radiation G value are estimated to be ∼2.002 and 0.5±0.2, respectively. When 3‐MP or 2‐methyl‐pentene‐1 (2‐MP‐1) containing CO2 is γ irradiated at 77°K, a singlet (g=∼2.0007; linewidth=∼3.1 G) and a flanking doublet with a splitting of ∼8 G are produced. The singlet, but not the doublet, shows saturation effects starting at ∼0.05 m...