Photo-double ionization of molecular hydrogen

The angular distribution of the correlated electron pair emitted in single-photon double ionization of the hydrogen molecule is analysed and calculated using a variety of approximations. Attention is directed particularly towards the differences between the molecular angular distribution and that of the corresponding 'united atom', i.e. that arising from the double ionization of helium. Qualitative agreement is obtained with recent experiments on photo-double ionization of the hydrogen molecule. The major effects arising from the two-centre nuclear field of the the molecule and the orientation of the axis at the moment of photon absorption are exposed in the simpler problem of photoionization of the H-2(+) ion.