Transverse relaxation loss of magnetisation in the x-y plane

Magnetic field differences in the sample can be considered to arise from two distinct sources. The first is simply from static magnetic field inhomogeneity throughout the sample volume, which is really an instrumental imperfection and it is this one aims to minimise for 

For most spin- /2 nuclei in small, rapidly tumbling molecules in low-viscosity solutions, it is field homogeneity that provides the dominant contribution to observed linewidths, and it is rarely possible to obtain genuine T2 measurements directly from these. However, nuclei with spin V2 (quadrupolar nuclei) may be relaxed very efficiently by interactions with local electric field gradients and so have broad lines and short T2S that can be determined directly from linewidths. 

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