Photodouble ionization differential cross sections for D2 with various electron energy sharing conditions

The mutual,angular distributions of the two ejected electrons following direct photodouble ionization-ha, e been measured for D-2 at an excess energy (E) of 25 eV using linearly polarized light. These (gamma; 2e) 'triple' differential cross sections (TDCSs) were obtained for asymmetric electron energy conditions with energy sharing ratios (R = E-2/E-1) of R= 24, 11.5, 4 and 2.57.;:In all cases the 'reference' electron (energy = E-1) was oriented along the direction of the electric field vector (epsilon) and detected in coincidence with a second electron (energy = E-2) coplanar with e and the photon beam direction (k(gamma)). For comparison, helium TDCSs were obtained for the same E and R values under nearly identical spectrometer conditions. These show very good agreement with the results of hyperspherical-K-matrix with semi-classical outgoing waves calculations, thus providing even more confidence in the D-2 TDCSs where there is as yet no accurate ab initio theory. The similarities and differences between the experimental results associated With the two targets are qualitatively discussed in terms of Feagin's model (Feagin J M 1998 J. Phys. B: At. Mol. Opt. Phys. 31 L729).