The first moment of the 1 H NMR line was thus computed at several stages of the polarization buildup. M 1 was not estimated by direct numerical computation of Equation 1, but because of its large width, especially at lower polarization levels, the resonance lines may not have completely returned to the baseline within the spectral width. Therefore, in order to avoid large numerical errors, the first moments were computed using Lorentzian fits of the spectra, which appeared acceptable for such symmetrical line shapes. The changes of the first moment upon increase of the signal intensity during a buildup experiment are depicted in Figure . The graph clearly shows the linear dependence of the first moment with the line intensity, therefore the polarization and the magnetization.