  We present experimental investigation on the fluorescence profiles observed
by excitation of the hyperfine transitions of the second resonance line of
potassium with a wavelength of 404.4 nm in dependence on the atomic density.
This leads to both direct decay of the excited level population to the ground
state (violet fluorescence), and to cascade decay via the first resonance lines
(infrared fluorescence). It has been shown that the behavior of these two
fluorescence profiles is different: increasing the atomic density, the violet
fluorescence profile exhibits a well-pronounced self-absorption dip, while the
infrared line does not show any narrow-width reduced absorption structure.
Moreover, the profiles of the infrared line have a higher signal-to-noise ratio
than that of the violet line. Our investigations show that beside atomic
population, atomic polarization is also transferred by the cascade transitions.
This is evidenced by registration of coherent magneto-optical resonances at the
two fluorescence lines. The signal-to-noise ratio of these resonances
registered at the first resonance line is significantly higher than at those
obtained at the second resonance line. The proposed study makes it possible to
examine cascade transitions in alkali atoms, particularly the preservation of
atomic polarization, i.e. the coherence transfer by cascade transitions.
