Saturation resonance

Figure 5. Typical incoherent population dynamics within the level scheme of Fig. 4 for fully saturated resonant transitions calculated from the rate equations (1).

Figure 8.26. The control ID spectrum (a) and NOE difference spectra (b and c) of 8.9 in MeOD. The difference spectra show only NOE enhancements and the truncated difference signal of the saturated resonance (arrowed). The observed enhancements are consistent with the indicated 2,5-dr geometry across the ring oxygen of 8.9.

It is experimentally possible to distinguish between population relaxation and pure dephasingf dynamics. In the population relaxation experiment, a saturating resonant microwave pulse causes an abrupt change of the populations of the triplet-state sublevels. Population relaxation ensues due to radiative and non-radiative decay out of the triplet state sublevels and due to spin-lattice relaxation. Experimentally, the temporal behavior of this population relaxation is probed. Further details are given in Sect. 4.2. 

Fig. 2. Graphic illustration of the saturation resonance observed in CO2 fluorescence at 4.3 pm. The figure shows an internal absorption cell within the laser cavity. External cells may also be used.

C. Freed and A. Javan, "Standing-Wave Saturation Resonances in the COj 10.6 y Transitions Observed in a Low-Pressure Room-Temperature Absorber Gas," App. Phys. Lett. J 7, 53 (1970). 

The investigations of N0 reveal two classes of results. On the one hand we find a confirmation or the prepared experimental situation. We obtain expected results. On the other hand nearly all experiments reveal more "structure" than expected. The unexpected experimental results are in disagreement with the conventional description of the prepared experimental situation. For instance in the "laser scanning" experiment we expect a saturation resonance whose width depends on the light intensity and approaches the value (2nXj, ) 5 kHz for vanishing light intensity. The amplitude of this resonance is expected to depend primarily on the population hole in the lower state. However, the experimental results are very different from these expectations. Experimental errors can be excluded. The same experiments are also performed on I2 with the same experimental apparatus. 

H.G.Weber Anomolous laser saturation resonances in N0 , Z.Phys.D-Atoms... 

Contents Introduction. Elements of the Theory of Resonant Interaction of a Laser Field and Gas.—Narrow Saturation Resonances on... 

Fig. 3.7 Observation of a narrow saturation resonance by use of a single strong coherent traveling wave and a countertraveling weak probe wave, (a) Experimental arrangement. A small part of the intense wave is reflected back through the cell. The attenuation of this weak wave is studied as a function of the laser-field frequency, (b) Molecular velocity distribution, showing velocity groups that interact resonantly with the strong wave and the probe wave, (c) Absorption of probe wave as a function of frequency.

Fig. 3.9 Observation of narrow saturation resonances associated with coupled transitions (a) energy-level diagram (b) detection scheme (c) absorption of probe wave for coupled transition m — 1 as a function of its frequency u>. ...

The refractive-index dispersion can be used to observe absorption hnes. This approach is also applicable to the observation of narrow dispersion saturation resonances within the Doppler profile. The first experiments along these lines were performed by Borde et al. (1973) by means of a ring interferometer containing an iodine-vapor-filled nonlinear-absorption cell. 

Saturation spectroscopy makes it possible to attain very high spectral resolution by means of ultranarrow spectral saturation resonances whose width is five to six orders of magnitude smaller than the Doppler width. Tunable lasers capable of an emission... 

This relation forms the basis for the search for the PVED effect in exactly those transitions for which ultranarrow saturation resonances were obtained. 

Fig,13.16. Schematic diagram showing stabilization of the frequency of a 6328 X He-Ne laser to one of the saturated resonances of iodine molecules contained in an intracavity absorption cell. 

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