ISOTOPE EFFECTS IN X-RAY-IRRADIATED ACIDIFIED H2O–D2O SOLUTIONS

Abstract

H2O–D2O mixtures containing 0.1–1 N H2SO4 were irradiated by 200-kv X rays. The molecular isotope effect, [Formula: see text], was determined from experiments on KBr solutions. The atomic isotope effect, [Formula: see text], was determined from experiments on ethanol solutions. At 96% D2O, αA = 3.7 ± 0.5 and αM = 4.0 ± 0.2. The isotope effects are discussed in connection with the radiation-chemical reaction H3O+ + eH2O → H + 2H2O. The connection between the atomic and molecular hydrogen is discussed. It is concluded that the relation between the observed atomic and molecular isotope effects is not contrary to a hydrogen atom recombination reaction leading to the molecular product. Isotope effects due to the oxidation of Fe+2 ions by hydrogen atoms in acid solutions were measured and the mechanism of this reaction is discussed.