Dynamic 2H nuclear magnetic resonance of rotating solids

The sensitivity of one-dimensional dynamic magic-angle spinning (MAS) and off-MAS 2H nuclear magnetic resonance spectra to changes in the parameters of jump-type molecular motions is studied. The Floquet theory approach is used to simulate spectra of spins with I = 1, which are involved in exchange processes in rotating solids. The solution of the Bloch-McConnell equations for rotating samples are derived and some simulated frequency spectra are shown. The dependence of the lineshapes of the center and sidebands of the MAS and off-MAS spectra on the exchange parameters are discussed. Experimental results of 2H spectra of perdeuterated dimethyl sulfone, obtained in the temperature range 20-55 degrees C, are demonstrated. The methyl groups in this molecule undergo pi flips at rates that can be detected by MAS and off-MAS NMR. The shapes of the experimental sidebands are compared with simulated results.