Multiplet labeling

This opens the Multiplet Options dialog box where the number of Distance Lines, the Capture Range, Drift Range, Min. Intensity, Min. Delta/J (first order criteria) and the orientation of the multiplet labels may be selected. 

The spectrum from Model 1 is reproduced below. Recall that a cluster with one peak is called a singlet, two peaks = doublet, three peaks = triplet, and four peaks = quartet. Any cluster with five or more peaks will be called a multiplet. Label peak clusters a and b, below, with singlet (s), doublet (d), triplet (t), quartet (q), or multiplet (m), as appropriate... 

Figure B2.4.3. Proton NMR spectrum of the aldehyde proton in N-labelled fonnainide. This proton has couplings of 1.76 Hz and 13.55 Hz to the two amino protons, and a couplmg of 15.0 Hz to the nucleus. The outer lines in die spectrum remain sharp, since they represent the sum of the couplings, which is unaffected by the exchange. The iimer lines of the multiplet broaden and coalesce, as in figure B2.4.1. The other peaks in the 303 K spectrum are due to the NH2 protons, whose chemical shifts are even more temperature dependent than that of the aldehyde proton.

Fig. 14 are the simulated distributions including the different parent rotational levels. An interesting observation from these distributions is that the shape of the multiplet peak corresponding to each 011 (/I) rotational level for the perpendicular polarization is not necessarily the same as that for the parallel polarization see for example the peak labelled v = 0, N = 22. From the simulations, relative populations are determined for the OH (A) product in the low translational energy region from H2O in different rotational levels for both polarizations. The anisotropy parameters for the OH product from different parent rotational levels are determined. Experimental results indicate that the ft parameters for the 011 (/I) product from the three parent H2O levels Ooo, loi, I11, are quite different from each other. Most notably, for the 011 (/I, v 0, N = 22) product the ft parameter from the foi H2O level is positive while the ft parameters from the Ooo and In levels are negative, indicating that the parent molecule rotation has a remarkable effect on the product anisotropy distributions of the OH(A) product. The state-to-state cross-sections have also been determined, which also are different for dissociation from different rotational levels of H2O. 

In analogy to 106, significant changes in the 13C NMR spectrum of 107 in THF are only observed for Cl and C3 compared with the neutral parent compound. The Cl 13C signal of a 6Li-labeled compound 107 is split into a six-line multiplet (Figure 52). 

We have labelled the three signals, two of which are additionally shown in an expanded form, and it is clear that the low-field signal, with the coupling of 9.4 Hz, must correspond to CP. We can see only one other coupling (39 Hz), which occurs in both of the other multiplets this must be between aP and bP. But which signal corresponds to aP and which to bP This information comes from the chemical shift of analogous compounds, where phosphonates such as aP absorb to high-field of 20 ppm, while phosphine oxides such as bP and CP absorb at around 30 ppm. 

The spin-orbit interaction, which couples L and S to give a total angular momentum J, splits the multiplets into their components labeled 2,v +1X /, where J is the total angular momentum quantum number. The spin-orbit splitting is given by (Bethe (1964))... 

The spin-orbit coupling term in the Hamiltonian induces the coupling of the orbital and spin angular momenta to give a total angular momentum J = L + S. This results in a splitting of the Russell-Saunders multiplets into their components, each of which is labeled by the appropriate value of the total angular momentum quantum number J. The character of the matrix representative (MR) of the operator R(0 n) in the coupled representation is... 

The labeling of the crystal-field multiplets according to the irreducible representations of a double group can be performed as follows. 

Focusing now our attention to our set of (t2g )3 states we observe that 2D and S are the MQ = 0 components of a quasi-spin singlet while 2P is the Mc = 0 component of a quasi-spin triplet. The full quantum structure of the (t2g)3 multiplets thus involves seven labels QMQSLTMsMry, albeit the Me label is redundant since all states share the same MQ value. 

Figure 7.18. The lowest tunneling multiplet of two coupled methyl groups. Symmetry labels and in-tramultiplet transition frequencies are indicated.

Due to the so-called /-mixing within the crystal field, multiplets with different / values are coupled. However, similar to the free-ion case, the levels are still designated by the principal 25+1L j component of the crystal-field wavefunction. For the further labeling of levels split by the crystal field, either the irreducible representation /j (Bethe, 1929) to which the particular wavefunction belongs or the crystal quantum number /i defined by Hellwege (1949) are most commonly used. 

In standard HFS calculations all electrons with the same n and l labels are assigned similar energies at the average of the multiplet for that level. Since all electrons at the valence level are unlikely to reach the ionization limit simultaneously, the energy in excess over the ground state must be redistributed so as to promote a single electron towards ionization. 

The spin-orbit interaction becomes more important as Z increases. The spin-orbit interaction is diagonal in 7, where 7 = L + S. The 25+1L multiplet is split into levels labeled by their 7 eigen values for example... 

Selective trapping of alkyl radicals from the alkyl halide component during the course of the catalytic disproportionation is the same as the previous observation with silver, and it indicates that the prime source of radicals in the Kharasch reaction lies in the oxidative addition of alkyl halide to reduced iron in Equation 47. Separate pathways for reaction of i-propyl groups derived from the organic halide and the Grignard reagent are also supported by deuterium labelling studies which show that they are not completely equilibrated.(49) Furthermore, the observation of CIDNP (AE multiplet effect) In the labelled propane and propene... 

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