It is shown that intense collisionless Raman-type extraresonant signals in four-wave mixing can be obtained by exciting a strongly fluorescent atomic or molecular eigenstate which is not directly connected to the states coupled by the Raman transition. The process which triggers the extraresonant signal is associated with resonance-enhanced three-photon scattering or, equivalently, with excited-state Raman scattering.

• Received 20 December 1982

DOI:https://doi.org/10.1103/PhysRevA.28.302