Interference in high-order above-threshold ionization

A generalization of the Keldysh ionization amplitude derived previously which incorporates rescattering is used to calculate above-threshold ionization spectra for medium-high intensity (similar to 10(14) W cm(-2)). Quantum interferences are identified and shown to be capable of causing above-threshold ionization peaks to rise and fall by an order of magnitude when the laser intensity changes by only a few per cent. The calculations are carried out for a zero-range binding potential. Comparison with available three-dimensional accurate calculations for a Coulomb potential shows sufficient agreement suggesting that predictions based on the zero-range potential are qualitatively reliable.