Molecular EIT: an initial state |g〉, residing in the ground electronic potential is excited by a weak laser pulse ε1 to a resonance state |e〉 in electronic state Q, which decays radiatively or non-radiatively to the continuum manifold of electronic state P. The |e〉 state is coupled optically to a third state |s〉 by a strong control field ε2 and undergoes as a result Autler-Townes splitting. As a result of the splitting and the decay, an EIT “hole” in the absorption of the probe field ε1 is formed at E = E e .
Two overlapping absorption lines related to two different vibronic transitions in two molecules.
EIT assisted spectroscopic probing. A strong control field eliminates one of the overlapping lines from the absorption spectrum. This field is not in resonance with any strong transition in the second molecule.
Use of EIT spectroscopy to resolve two overlapping lines. The two overlapping absorption lines are shown as dotted blue and solid red lines. Their joint envelope is shown by the dashed black line. In the upper panel, the spectrum is unperturbed. In the lower panel, one of the absorption lines has been AT-split and removed from the spectrum.
Few close lying transitions of the control field which are close to the probe transition frequency too. We demonstrate the behavior of the spectrum in several control amplitudes. (a): Ω c = 0Γ; (b): Ω c = 2Γ; (c): Ω c = 4Γ; (d): Ω c = 6Γ.
(a) ERE-CARS. The pump and Stokes laser pulses create a Raman coherence in a molecule. The Probe drives a resonant transition into an excited electronic state |s〉, leading to emission at the frequency ω as = E s − E g . (b) EIT-assisted CARS scheme. The pump and Stokes pulses create a Raman coherence, and the CW Probe drives emission at the anti-Stokes frequency, ω as = ω e + ω Probe . The control field, applied simultaneously with the Probe, suppresses emission at the frequency ω as .
Overlapping lines in 35, 35Cl2 and 35, 37Cl2. The letters P and R refer to the rotational branches ΔJ = ±1.
Overlapping lines in CH3OH.35
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