Quadrupolar transitions

Fig. 10 a Co K-edge XAS spectrum for CoP collected in transmission mode, showing the approximate regions where XANES and EXAFS features are observed and the assignment of dipolar and quadrupolar transitions, b EXAFS (x) vs. k curve, c Fourier transform of EXAFS... 

The first-order quadrupolar transition frequency under MAS is then given by... 

Sum-frequency generation (SFG) at second-order and the nonlinear Raman spectroscopy BioCARS at fourth-order can also probe chiral molecules. They have no analog in linear optics. We show that both are only symmetry allowed in a fluid, if the fluid is chiral. However, in contrast to optical activity phenomena, these processes arise entirely from induced electric-dipoles (without magnetic or quadrupolar transitions) and they are not circular differential. All laser beams can be linearly polarized and no polarization modulation is required as the detection of a sum-frequency (yiz. five-wave mixing) photon is in itself a measure of the solution s chirality. Since an achiral solvent can not contribute to the signal, these techniques are sensitive, background-free probes of molecular chirality. The SFG... 

Table 6. The wavenumber (jr/lO cm ) and the observed and the calculated d-d rotational strength (R/10 Debye Bohr magneton) of the quadrupolar transitions in the quasitetrahedral [Co(diamine)Cl2] complexes containing the diamines, (-)-spaitein(II) and (-)-a-isospartein(in),...

Within the compounds with equivalent sites for Ce, the specific heat of Cc4Bi3 also shows two well-defined peaks (Suzuki et al. 1987). This compound lies on the borderline between regions I and II, it is actually ferromagnetic for T < 3.5 K but after undergoing a first-order transition. The entropy gain including the transition at 3.8 K is 0.8I ln2 at 20 K. The field dependence of the specific heat in this compound was compared by the authors with that of CeBg, where a quadrupolar transition was observed by neutron diffraction. 

Granger, P. Quadrupolar Transition Metal Lanthanide Nuclei. In Encyclopedia of Nuclear Ma etic Resonance-, Grant, D. M., Harris, R. K.,... 

The nuclear transitions involved in Mossbauer spectroscopies (MS) are varied in the most relevant elements. In this way, Fe and Sn have simple quadrupolar transitions between I = 3/2 and 1/2, although having a different sign in the... 

According to the dipole selection rules, photoexcitation of a core electron with angular momentum I probes the I 1 components of the final state. In the Lm absorption processes I — 1 transitions (2p - 6s) can be neglected. Their probability is less than 3% of the / -I-1 (2p - 5d) transition probability (cf., e.g., Barinski and Nefedow 1969). The contribution of quadrupolar transitions to the absorption coefficient can also be neglected. Quadrupolar transitions turn out to be important only in the higher Z elements (in Lnm absorption for Z > 70). Calculated ratios of quadrupolar to dipole transitions for K and L absorption are given in table 2 (Muller and Wilkins 1984). 

The nucleus is the only one among the quadrupolar transition metals with a relatively low quadrupole moment and a high receptivity, and is hence a particularly well-suited NMR probe even in... 

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