Effect of Inert-Gas Moderators on the (n, γ) Activated Reaction of I128 with CH4

In the presence of a large excess of gaseous methane, 54.4±0.5% of I128 formed by (n, γ) activation was found to become stabilized in organic combination. The effects of inert-gas additives in moderating the reaction of I128 with CH4 were determined in an effort to ascertain the mechanism. The data, extrapolated to zero mole-fraction methane, indicate that xenon is capable of reducing the organic I128 to 11% whereas neon, argon, and krypton each reduce it to only about 36%. These data suggest that of the 54.4% organic I128, about 18.4% forms as a result of hot I128 reactions, 11% as a result of excited iodine atoms or I+ ions in the 3P2, 3P1, and/or 3P0 states, and 25% as a result of reactions of I+(1D2) ions.