Two-photon ionisation of caesium ground state: theoretical calculation of the interference minimum near the 7p resonance

The two-photon ionisation cross sections of Cs atoms near the 7p resonance has been calculated for linearly and circularly polarised light. The use of a model potential allows the authors to take into account spin-orbit effects and to perform the infinite summations involved in second-order perturbation theory. The predictions obtained are in good agreement with recent experimental data. Moreover, the authors show that the contribution of continuum intermediate states cannot be neglected.