Quasi-Landau spectrum of a hydrogen like atom in a high magnetic field

A two dimensional semiclassical approximation is used to examine the σ polarization spectrum of a hydrogen like atom in a strong magnetic field. Resonances above the zero field ionization limit are found and their energy separations are computed over the region from the ionization limit to 40 ħωc above, where ωc is the cyclotron frequency, for magnetic fields of 10, 17, 25, 32, 40 and 47 kG. At the ionization limit the separation between resonances is found to be 1.500 ħωc, independent of magnetic field strength, which is in agreement with a separation of 1.5 ħωc observed experimentally by Garton and Tomkins (1969) in the sigma polarization spectrum of barium in a magnetic field of 24 kG. The energy separations are found to decrease above the ionization limit toward the value ħωc, which is characteristic of the levels of a free electron in a homogeneous magnetic field.