ANGULAR ELECTRON CORRELATIONS NEAR THE DOUBLE-IONIZATION THRESHOLD

The electron angular distribution near the double ionization threshold is considered in the framework of the Wannier mechanism. The problem is reformulated in the physically appealing terms of the harmonic oscillator with time-dependent frequency. The characteristic features of the process are described in terms of the time propagation in the adiabatic regime and the deviations from it. The boundary conditions at the border of the reaction zone are crucial for the final relative angular distribution. The omission of this point is shown to invalidate previous calculations. The simplest possibility to formulate a reasonable boundary condition comes from the assumption of the oscillator zero-mode population at the border of the reaction zone. The deficiencies of this formulation necessitate consideration of arbitrary boundary conditions; for this case the general solution of the propagation problem is presented.