The reaction H + H -> H2 in solution: yields of ortho- and para-hydrogen

It is proposed that the reaction, H + H -> H2, can only take place if the atoms meet in a singlet state. Triplet pairs of of atoms will separate, but re-encounters are probable and the spin wave-function may change because of the electron-proton hyperfine interaction: the rate of this process can be altered by applied magnetic fields. A kinetic model has been developed to study the effects on the reaction rate and on the ortho/para ratio of the hydrogen produced. The predicted effects are small but should be detectable because of their distinctive field dependence. (author)