Atomic Diamagnetism: Quasi Landau Spectrum near the Ionization Threshold

The positions of quasi Landau resonances as a function of magnetic field strength are reported for the first time. These resonances were observed near the ionization limit in the even-parity channels of barium and strontium with use of two-photon laser spectroscopy. The change in the resonance positions as the field strength is varied and the energy spacings of the resonances agree well with hydrogenic semiclassical theory. Resonance profiles, but not positions, are found to be species dependent.