  Resonance transitions between the Zeeman sublevels of optically-polarized Rb
atoms traveling through a spatially periodic magnetic field are investigated in
a radio-frequency (rf) range of sub-MHz. The atomic motion induces the
resonance when the Zeeman splitting is equal to the frequency at which the
moving atoms feel the magnetic field oscillating. Additional temporal
oscillation of the spatially periodic field splits a motion-induced resonance
peak into two by an amount of this oscillation frequency. At higher oscillation
frequencies, it is more suitable to consider that the resonance is mainly
driven by the temporal field oscillation, with its velocity-dependence or
Doppler shift caused by the atomic motion through the periodic field. A
theoretical description of motion-induced resonance is also given, with
emphasis on the translational energy change associated with the internal
transition.
