Growth of NMR multiple-quantum coherences in quasi-one-dimensional systems

It is shown that the second moment of the MQ-NMR intensities distribution is a convenient parameter for the quantitative description of the growth of MQ coherences. With the exact solution for the xx-model Hamiltonian the dependence of this second moment upon the preparation time in the MQ sequence is explicitly related to the structure of the sample. Calculations for a quasi-one dimensional system of uniformly-spaced spins forming a linear chain that take into account both intra- and interchain interactions are compared to experimental data.