Abstract
The response to a monochromatic field of a three-level system, in which the (1,2) interval is relatively close to the (2,3) interval and the associated dipole matrix elements are arbitrary, is examined. It is found that, for weak pumping, proper detuning from exact two-photon resonance toward the more strongly coupled frequency produces a spin-½-type Rabi oscillation between levels 1 and 3, while proper detuning at strong pumping in the opposite direction produces a spin-1-type oscillation.