ATOMIC RESONANCES IN PARALLEL ELECTRIC AND MAGNETIC-FIELDS

In a quantum mechanical treatment, an atom in external parallel electr ic and magnetic fields ionizes at energies above the classical ionizat ion threshold and, at energies below tunnels through a potential barri er, in each case forming quasi-bound states (resonances). Such resonan ces can be calculated for hydrogen using the complex-coordinate method . The combination of this method with the R-matrix method allows the c orresponding resonances to be calculated for non-hydrogenic Rydberg at oms. We employ such a combination of methods in an investigation of th ese resonances in sodium for various relative strengths of parallel, l aboratory strength, external fields. Results are also presented for hy drogen in strong fields.