Abstract
Level-crossing effects have been detected non-optically with the use of a Rabi-type atomic-beam method. The sodium beam was excited by intense linearly polarised radiation from a CW narrow-band dye laser. Several superimposed resonances were observed in the atomic-beam signal when scanning the magnetic field around zero. The two narrower resonances are interpreted as high-order non-linear effects. They arise from the coupling of laser-induced Zeeman coherences in the ground state (including a hexa-decapole moment) with the populations of the Zeeman sublevels.