| Popis: |
The radiolysis of liquid ammonia has been studied, using the high LET He- and Li-recoil particles from the 10B (n, α)7Li- process. Suitable boron compounds such as H3NBF3 and B(OC2H5)3 were dissolved in anhydrous liquid ammonia and irradiated with thermal neutrons of a nuclear reactor. Up to doses of about 1021 eV/g almost dose-independent G(N2H4)- values of 1·5 ± 0·2 were obtained. Comparison with the γ- and fission fragment-radiolysis shows the expected LET- dependence of the hydrazine yield [γ-radiolysis < 10B(n, α)7Li < 235U (n, f)]. In the 10B(n, α)7Li-radiolysis, however, (using 3·2 mole %H3NBF3 in liquid ammonia) the N2H4-concentration continues to increase at higher doses, a steady-state concentration not being reached, even at some 1022 eV/g. Comparative studies on the γ-radiolysis of liquid ammonia in the presence of boron compounds indicate that Lewis acids of the type BX3 (X = F, OC2H5, C3H7,C6H5) or their NH3-adducts exhibit strong protection effects against radiation decomposition of the hydrazine formed, thus causing a considerable increase in yield. |
