Design of a triple quantum coherence excitation schemefor protons in solid state NMR

摘要

We present a rf scheme designed to excite triple quantum (TQ) coherences for proton solid stateNMR. This recoupling scheme is based on the phase modulated Lee Goldburg sequence combinedwith echo pulses and applied nonsynchronous with the magic angle spinning period. Based on theeffective bimodal Floquet Hamiltonian we optimize the conditions for TQ coherence excitation.Numerical simulations are used to further adjust the recoupling conditions as well as define thesequence limitations. Experimental TQ filtered one-dimensional spectra and two-dimensionalcorrelations of TQ to single quantum coherences are presented for-standard amino acids. Theseresults are compared with the crystal structures showing that this scheme can aid in resonanceassignments and in resolving local spin topologies.