Multi-dimensional experiments

In NMR, the magnetization in the xy plane is detected, so it is the expectation value of the operator that is measured. This is just the unweighted sum of all the operators for the individual spins . It may be a fimction of several time variables (multi-dimensional experiments), including the tune during the acquisition. 

Multi-dimensional experiments based on the PISEMA sequence also dramatically enhanced the resolution of peaks and enabled the measurement of multiple NMR parameters.These parameters are orientation dependent and have been shown to be useful in determining the orientation of the peptide plane with respect to B. Chemical shift and dipolar coupling... 

MAS) to remove the effects of the anisotropic nuclear spin interactions from one dimension of a multi-dimensional experiment.2 In the review period, one nice development in this area is the use of magic-angle turning... 

As in solution state NMR, the extension of experiments into two or more dimensions is the path used to gain the resolution required to measure multiple, large anisotropic interactions (dipolar coupling, CSA) that are accessible in solids. Experiments that focus on homonuclear multi-dimensional experiments include /-mediated correlation and dipolar-mediated H 2D double quantum... 

For the chemist today, the importance of solution-state NMR is well established. Individual nuclei within a molecule are differentiated on account of their chemical shift, while connectivities, which permit spectral assignment, are identified by through-bond J couplings. Through-space proximities, which yield information about three-dimensional structure, are accessible by experiments which exploit the nuclear Overhauser effect (NOE). Moreover, a host of multi-dimensional experiments have been developed which further enhance the information content [1, 2]. In many cases, however, the most appropriate sample to study molecular structure and dynamics is the solid. The purpose of this article is to give an overview of the different solid-state NMR methods which are available in such cases. Our focus is on the structural and dynamic information which a particular method can dehver, and, at most, only a simple qualitative explanation of how the experiment works will be given, although the relevant literature will always be cited, such that the interested reader can find details about, e. g., the experimental implementation. 

Data about chain alignment and reorientation must usually be obtained by modelling or simulation of the lineshape, and usually, data from several different experiments are required to yield an unambiguous conclusion. An exception involves the more recent multi-dimensional experiments, described in section 8.5 [53, 59], that are designed to yield the appropriate data graphically or with simple calculation. Even with 2-D spectroscopy, if multiple motions are present or if diffusion is also present, there remains a requirement to model the data. 

The objective of this chapter is to provide an overview of the currently available multi-functional techniques utilized in polymer analysis and identify those features of hyphenated methods that may play a key role in the future polymer analysis. The discussion centers around synergistic aspects of hyphenated techniques, their potential, error analysis, and utilization in multi-dimensional experiments. 

This chapter has shown, using Al-based fluorides as examples, that current and emerging solid state NMR methods may provide valuable answers to structural questions of relevance in material science. New improvements may be expected for dipolar coupled nuclei from the combination of very fast MAS with multiple quantum and multi-dimensional experiment at very high magnetic field. 

Natural convection in the molten pool causes the energy transport to be a multi-dimensional. Experiments have shown that most of the energy... 

---