Population trapping in the neon 2p₃to 1s₄transition

The fluorescence observed when a single-mode laser drives the 2p 3 (J=0) to 1s 4 (J=1) neon transition displays a narrow minimum as an applied magnetic field is varied. A detailed theoretical analysis of the system confirms that this resonance is due to the formation of a Zeeman coherence in the lower level which traps the population there. The dominant contribution to the population trapping comes from the atomic velocity classes for which the atom-laser detuning is close to zero, and for the case of exact resonance analytic expressions are obtained for dip width and depth. A broad minimum which also appears in the profile is shown to originate from incoherent processes in the atomic ensemble.