Molecular final-state interactions in triton β decay

The lowest order correction to the sudden approximation is formulated for the molecular transition amplitude in triton decay by taking account of the Coulomb interaction of the ejected β ray with residual charged particles. The effect is of the order of (α/βe)2 with βe the β-electron velocity. The transition probabilities for propane are explicitly calculated by an ab initio SCF-MO method and the modification is shown to be at most 0.6 % for those in the sudden approximation. (author)