Beat resonance ground state

Consider now the resonance limit, when only a small number of eigenstates is involved. In this limit a true quantum beat spectrum is obtained. For simplicity of presentation we consider a three-level system in which the closely spaced coherently excited levels fa and fa decay into the ground state. The total number of photons counted is just... 

Auzinsh, M.P., Nasyrov, K.A., Tamanis, M.Ya., Ferber, R.S. and Shalagin, A.M. (1990). Determination of the ground-state Lande factor for diatomic molecules by a beat-resonance method, Chem. Phys. Lett., 167, 129-136. 

Auzinsh, M.P. (1990). Nonlinear phase resonance of quantum beats in the dimer ground state, Opt. Spectrosc. (USSR), 68, 750-752. 

The shape of this spin excitation is directly mirrored in the shape of the retrieved anti-Stokes pulse. The resonant classical read laser beats with the ground-state coherence S(z, t) and converts the atomic spin wave into an anti-Stokes field as(s, t) the number of anti-Stokes photons emitted per unit time from the end of the cell is driAs(t)/dt = c S L, t) as(L, t))/L. Note that the read laser establishes an EIT configuration for the generated anti-Stokes field, so that the anti-Stokes light propagates unabsorbed through the... 

As already mentioned, electronically resonant, two-pulse impulsive Raman scattering (RISRS) has recently been perfonned on a number of dyes [124]. The main difference between resonant and nom-esonant ISRS is that the beats occur in the absorption of tlie probe rather than the spectral redistribution of the probe pulse energy [124]. These beats are out of phase with respect to the beats that occur in nonresonant ISRS (cosinelike rather tlian sinelike). RISRS has also been shown to have the phase of oscillation depend on the detuning from electronic resonance and it has been shown to be sensitive to the vibrational dynamics in both the ground and excited electronic states [122. 124]. 

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