NUMERICAL AND THEORETICAL-ANALYSIS OF MULTIQUANTUM MAGIC-ANGLE-SPINNING EXPERIMENTS

Using a recent investigation of the Floquet's theorem for magic-angle spinning nuclear magnetic resonance simulations (NMR), a procedure for computing multiquantum magic-angle spinning spectra is derived. The g eneral formalism which is introduced here can be applied more generall y to any solid-state NMR two-dimensional experiments. All interactions and their time dependency are considered during the pulses. Furthermo re, for powder patterns, a formal average is possible on gamma (the th ird component of the Euler angle describing the orientation of the cry stallite) which leads to great simplifications and to an improved comp uting efficiency. As an application, the intensity of the spinning sid ebands in,the two-dimensional multiquantum magic-angle spinning spectr um is investigated. The recently reported appearance of numerous spinn ing sidebands in the multiquantum dimension is discussed. Such effects appear naturally in the present formalism which Provides a theoretica l framework for:further investigations. Simulations of two-dimensional spectra are compared with experimental data. (C) 1998 American Instit ute of Physics. [S0021-9606(98)00132-9].