Suppose a sample of atoms (say rubidium), which is exposed to constant magnetic field, is irradiated with circularly polarized light so that the electrons are excited from lower S level (F=3) to P level (F'=4).
Then the fluorescence signal is to be recorded while the frequency of a linearly polarized radio-frequency magnetic field is swept across the resonances.
My question is: how does the sweeping of frequency of a linearly polarized radio-frequency field across the resonances help for fluorescence detection?
