Transfer of transverse magnetization

Doubly selective ID-TOCSY experiments have been proposed to specifically transfer in-phase magnetization from two designated spins [57, 58]. This transfer will only take place if the two spins are connected by a scalar coupling. This method is achieved by using a double-selective spin-lock after the selective excitation of transverse magnetization of a desired spin. The doubly selective spin-lock can be obtained by using cosine-modulated... 

Preparation, evolution and detection are the time periods of pulse sequences described for. /-modulated spin-echo and polarization transfer experiments. The basic FT NMR technique operates without any evolution period tt immediately after generation of transverse magnetization (preparation) its free induction decay S(t2) is detected. Subsequent Fourier transformation provides the FT NMR spectrum S (f5). 

Fig. 7.2.31 Filters for homonuclear coherent magnetization transfer. All filters start from and end with longitudinal magnetization, (a) Selective excitation and reconversion of coherences with a nonselective mixing period, (b) Realization of a nonselective mixing period in a z filter via longitudinal magnetization, (c) Nonselective excitation and reconversion of coherences with a selective mixing period, (d) Realization of a selective mixing period by a multi-quantum filter, (e) Selective exchange of transverse magnetization within the multiplets of coupled homonuclear spin pairs by a homonuclear version of the INEPT method.

Notice that dephasing of the transverse magnetization does not affect Mz a T2 process involves no energy transfer but, being a spontaneous process, does involve an increase in the entropy of the spin system. 

The effort to solve Eqs.(l) evidently depends on the refractive index profile. For isotropic media in a one-dimensional refractive index profile the modes are either transversal-electric (TE) or transversal-magnetic (TM), thus the problem to be solved is a scalar one. If additionally the profile consists of individual layers with constant refractive index, Eq.(l) simplifies to the Flelmholtz-equation, and the solution functions are well known. Thus, by taking into account the relevant boundary conditions at interfaces, semi-analytical approaches like the Transfer-Matrix-Method (TMM) can be used. For two-dimensional refractive index profiles, different approaches can be... 

The last three pulses listed in table 1, namely the two E-BURPs and the are non-universal pulses designed to transfer Zeeman polarization Iz) into detectable transverse magnetization I or ly), but not to achieve the reverse operation. The conversion of or ly into Iz can be achieved by using the time-reversal of the considered pulse shape. An alternative... 

A first pulse create.s transverse magnetization components (coherences) which evolve in the evolution period tl (DO in the schemes) with their characteristic precession frequencies (chemical shift and homonuclear J-coupling). The effect of the second (mixing) pulse is that information from one nucleus that evolves in tl is transferred to another (J-coupled) nucleus, the magentization components of which evolve and are detected in t2. Therefore, the nuclei carry information that relates not only to their own chemical shifts and coupling constants but also the corresponding information about the other, coupled spins. 

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