title: Ergodicity and efficiency of cross-polarization in NMR of static solids.
abstract: Cross-polarization transfer is employed in virtually every solid-state NMR experiment to enhance magnetization of low-gamma spins. Theory and experiment is used to assess the magnitude of the final quasistationary magnetization amplitude. The many-body density matrix equation is solved for relatively large (up to N=14) spin systems without the spin-temperature assumption for the final spin states. Simulations show that about 13% of the thermodynamic limit is still retained within the proton bath. To test this theoretical prediction, a combination of a reverse cross-polarization experiment and multiple contacts is employed to show that the thermodynamic limit of magnetization cannot be transferred from high- to low-gamma nuclei in a single contact. Multiple contacts, however, fully transfer the maximum magnetization. A simple diffusion on a cone model shows that slow dynamics can affect the build up profile for the transferred magnetization.
authors.affiliation: Department of Chemistry, North Carolina State University, Raleigh 27695-8204, NC, USA. alex_nevzorov@ncsu.edu
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Nevzorov
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D004058:Diffusion; D004574:Electromagnetic Fields; D004578:Electron Spin Resonance Spectroscopy; D007930:Leucine / Q000031:analogs & derivatives / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008565:Membrane Proteins / Q000737:chemistry
chemical_list: D008565:Membrane Proteins; D007930:Leucine; C088117:acetylleucine