Triple-quantum coherences

The strongest residual dipolar couplings were also edited in a non-rotating crosslinked poly(isoprene) series by exciting DQ and triple-quantum coherences in the short time regime [62,63]. From this, the dynamic order parameters of the methylene and methyl groups were estimated and correlated with the crosslink density. Essentially the same behaviour was found as for SBR. 

The three-dimensional HTQC-TOCSY and HQQC-TOCSY experiments use multiplicity filtering of CH2 and CH3 via DEPT-like (Doddrell et al., 1982) excitation and selection of heteronuclear triple-quantum coherence (HTQC) or quadruple-quantum coherence (HQQC Kessler et al., 1990b Kessler and Schmieder, 1991 Seebach et al., 1991). Other three-dimensional experiments with DEPT editing include DEPT-TOCSY (Schmieder et al., 1990, 1991b) and the DEPT-HaOselH experiment of Emerson and Montelione (1992b). 

Heteronuclear multiple-quantum correlation Experiment for tailored correlation spectroscopy of H and H resonances in peptides and proteins Homonuclear Hartmann-Hahn spectroscopy Heteronuclear quadruple-quantum coherence Heteronuelear triple-quantum coherence Heteronuclear single-quantum coherence TOCSY sequences developed at the Indian Institute of Chemical Technology Insensitive nucleus enhancement by polarization transfer... 

Interconversion of single- and triple-quantum coherences was first suggested by Vega and Naor, who demonstrated how application of amplitude-modulated pulses, having a modulation frequency equal to the 13/2) 11/2) satellite transition frequency t i/2,3/25... 

During the 6 period, the triple-quantum coherence undergoes both CSE and relaxation. Applying the CSE operator gives... 

As in the case of two spins, the presence of more than one transverse operator in the product represents multiple quantum coherence. For example, 2IlxI2x is a mixture of double- and zero-quantum coherence between spins 1 and 2. The product 4/, xI2J3z is the same mixture, but anti-phase with respect to the coupling to spin 3. Products such as 4IlJ2J3x contain, amongst other things, triple-quantum coherences. 

The collective behavior of spins can be roughly understood as a simultaneous flip of two (double-quantum coherence), three (triple-quantum coherence), or more spins (multiple-quantum coherence). In other words, the spin system coherently exchanges two, three, or AM photons, respectively, with the resonant... 

When applied to longitudinal magnetization, the C7 sequence in general excites even-order multiple (double)-quantiun coherences. Applying C7 to transverse magnetization, in general leads to excitation of odd-order multiple-quantum coherences. Using POST-C7, triple-quantum coherence in fully C-labelled L-alanine has been excited in this way, with a triple-quantum filter efficiency of 8% for the central and 4% for the two peripheral spins. ... 

In one of the most simple 3Q/MAS NMR experiments, a large amount of triple-quantum coherence (3Q) is generated by the first, very strong rf pulse [71] (Fig. 15). This 3Q coherence subsequently evolves during the first-detection period ti with a frequency that corresponds to the triple fre-... 

Table 2, for the triple-quantum coherence of a spin with the param-... 

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