Spin labeling basic principles

The basic principle of 0-REDOR can also be directly utilized for purposes of spin counting, as the dephasing of spin Si as a function of the flip angle 0 depends on the number of spins S, coupled to Si. Cull et al. have recently followed this approach to determine the number of C (S,) spins coupled to (Si) in multiply C-labelled DL-alanine and the number of N (S,) spins coupled to C (Si) in U- C, N-labelled urea. 

Nuclear spin-labelling is a reporter group technique. The basic idea underlying this method is to introduce nuclear spins as probes into the system of interest and to deduce from the observed nuclear magnetic resonance (NMR) spectra valuable information about the order and dynamics of the molecular environment. In this chapter we will discuss the principle of the method and some recent applications to liquid crystal polymers. 

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