THE N-ELECTRON COULOMB CONTINUUM

It is shown that, when the n-electron continuum state is treated in LS -coupling, both the amplitude and the cross section for photo-and elec tron-impact ionization to such a state can be expressed as a linear co mbination of n-polar harmonics in the angles of emission of the n elec trons. The analysis utilizes re-coupling techniques, largely avoiding redundant sums over products of Clebsch-Gordan coefficients. The Clebs ch-Gordan series is generalized to n particles. Two selection rules ar e proved and the operation of such selection rules is illustrated by c alculations of-the differential cross section for (i) the complete pho to-fragmentation of the lithium atom and (ii) the complete fragmentati on of the helium atom under electron impact.