Postcollision interaction in the coincident emission of photoelectrons andanger electrons at small relative angles

Postcollision interaction effects have been investigated for sequential two -electron emission in xenon for particular kinematical conditions, small re lative angles between the emitted electrons, and selected energies epsilon( a) = epsilon(b) which are halfway in between the nominal values of the "pho to"-electron and the "Auger" electron. The experimental results are in good agreement with the theoretical prediction. Our successful technique to mea sure two coincident electrons of nearly the same energy and the same direct ions opens a plethora of possibilities to probe for different cases the Cou lomb interaction of three charged particles and the impact of the intermedi ate resonance state. [S0031-9007(99)09343-6].