Recoil doublet

Fig. 9.2 Generation of the recoil doublet of Lamb dips (a) population peaks in the upper-state population for coo (b) Bennet holes in the lower-state population (c) recoil doublet in the output power Pl(co) of the laser...

Fig. 9.3 Schematic experimental arrangement for measuring the recoil splitting and the measured signal of the recoil doublet of the hyperfine component 8 7 of the (P(7), V3) transition at X = 339 pm in methane [1115]...

Observation of Recoil Doublets and Suppression of One Recoil Component... 

The increased spectral resolution obtained with the Ramsey technique because of the increased interaction time allows the direct observation of recoil doublets in atomic or molecular transitions (Sect. 9.1.1). An example is the Ramsey spectroscopy of the intercombination line in calcium at k = 657 nm [1268], where a linewidth... 

Fig, 13,8. Recoil shift of Bennet holes in the lower state population (b) and of Bennet peaks in the upper state population (a). Recoil doublet in the output of a laser with internal absorption cell, generated by the shift of the Lamb dip against the Lamb peak... 

Using the value t = 0.2 for the effective thickness, the amount of resonance nuclei ( Fe) for a good thin absorber can be easily estimated according to the relation = tl(fA-(to)- For a quadrupole doublet with two equal absorption peaks of natural width and a recoil-free fraction of the sample/a = 0.7 one obtains... 

After reduction in H2 at 675 K, the catalyst consists mainly of metallic iron, as evidenced by the sextet (S = 0.00 mm s 1, H = 331 kOe), along with some unreduced iron, which gives rise to two doublet contributions of Fe2+ and Fe3+ in the center. The overall degree of iron reduction, as reflected by the relative area under the bcc-ion sextet, is high. One should not consider the relative spectral contributions as concentrations, however, because the three types of iron species may have different recoil-less fractions. 

The spectrum of [Au7(PPh3)7][OH] shows two doublets thought to correspond to the axial and equatorial Au atoms of a pentagonal bipyramidal cluster. However, the area ratio of the two subspectra is approximately 1.4 1 instead of the expected 0.4 1. Even when the expected relative intensities are treated to take the effective masses of the recoiling units into account, as described by Parish, Salter, and co-workers (111), the expected ratio increases to only 0.48 1. 

The area of the peaks in each Mossbauer doublet roughly corresponds to the amount of Fe actually present in that site (in fact, this is often assumed), but with some caveats. The first of these is the effect of differential recoil by Fe atoms in different sites. It is well-known that the area of a Mossbauer doublet (pair of peaks) is a function of peak width r, sample saturation G(x), and the Mossbauer recoil-free fraction/ Bancroft (1969 1973) uses the following formulations for area ratios in a mineral where there is only a single site for Fe, and it may be occupied by either Fe or Fe ... 

The spectra in Fig. 7 can be readily interpreted from the mobility of the ethylene molecules. When an ethylene molecule is sorbed on a ferrous ion the ion is pulled out of the plane of the window and when the molecule jumps away the ion relaxes to its original position. Hence the ions are forced to oscillate perpendicularly to the plane of the window and the oscillation decreases the recoil free fraction which reduces the area under the doublet. As more ethylene is added the number of unoccupied ferrous sites decreases and the residence time of an ethylene molecule on any one site is increased. Hence the recoilless fraction... 

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