Defining the sampling space in multidimensional NMR experiments: What should the maximum sampling time be?

Efficient sampling of signals is a key issue for multiple-dimensional NMR experiments to establish the best ratio between experiment time and spectral quality. Focussing on the most widely used sampling strategy using standard rectangular sampling and data analysis by Fourier transformation, a central question is concerned with determining the optimal maximum sampling time in the individual dimensions. The spectral resolution depends directly on this choice, as do the overall experiment times when addressing the indirect dimensions. We present a theoretical, numerical, and experimental analysis of the sampling space problem and propose approaches to efficient sampling for typical cases.