Pulse excitation vector model

To verify the theory of PIP, a computer program using C language was developed. It can be used to directly calculate the excitation profiles by PIPs or any other RF pulses. The calculation is based on the Bloch vector model for a non-interacting spin-1/2 system, where the spin-lattice relaxation during the pulse is neglected. The basic idea of the program is discussed as follows. 

The BIRD pulse [14] is in fact a cluster of pulses (Fig. 6.12) used as a tool in NMR to differentiate spins that possess a heteronuclear coupling from those that do not. The effect of the pulse can vary depending on the phases of the pulses within the cluster, so we concentrate here on the selective inversion described above. For illustrative purposes, proton pulse phases of x, y, X will be considered as this provides a clearer picture with the vector model, although equivalent results are achieved with phases x, x, —x, as in the original publication. The scheme (Fig. 6.14) begins with a proton excitation pulse followed by a spin-echo. Since carbon-12 bound protons have no one-bond... 

Chapter 3 introduces the vector model of NMR. This model has its limitations, but it is very useful for understanding how pulses excite NMR signals. We can also use the vector model to understand the basic, but very important, NMR experiments such as pulse-acquire, inversion recovery and most importantly the spin echo. 

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