TY  - JOUR
AB  - We present a detailed analysis of the radiofrequency (RF) field over full volume of a rotor that is generated in a solenoid coil. On top of the usually considered static distribution of amplitudes along the coil axis we describe dynamic radial RF inhomogeneities induced by sample rotation. During magic angle spinning (MAS), the mechanical rotation of the sample about the magic angle, a spin packet travels through areas of different RF fields and experiences periodical modulations of both the RF amplitude and the phase. These modulations become particularly severe at the end regions of the coil where the relative RF amplitude varies up to ±25% and the RF phase changes within ±30°. Using extensive numerical simulations we demonstrate effects of RF inhomogeneity on pulse calibration and for the ramped CP experiment performed at a wide range of MAS rates. In addition, we review various methods to map RF fields using a B0 gradient along the sample (rotor axis) for imaging purposes. Under such a gradient, a nutation experiment provides directly the RF amplitude distribution, a cross polarization experiment images the correlation of the RF fields on the two channels according to the Hartmann-Hahn matching condition, while a spin-lock experiment allows to calibrate the RF amplitude employing the rotary resonance recoupling condition. Knowledge of the RF field distribution in a coil provides key to understand its effects on performance of a pulse sequence at the spectrometer and enables to set robustness requirements in the experimental design.
AU  - Tošner, Z.*
AU  - Purea, A.*
AU  - Struppe, J.O.*
AU  - Wegner, S.*
AU  - Engelke, F.*
AU  - Glaser, S.J.*
AU  - Reif, B.
C1  - 51986
C2  - 43636
CY  - San Diego
SP  - 20-32
TI  - Radiofrequency fields in MAS solid state NMR probes.
JO  - J. Magn. Reson.
VL  - 284
PB  - Academic Press Inc Elsevier Science
PY  - 2017
SN  - 1090-7807
ER  - 

TY  - JOUR
AB  - High resolution proton spectra are obtained in MAS solid-state NMR in case samples are prepared using perdeuterated protein and D(2)O in the recrystallization buffer. Deuteration reduces drastically (1)H, (1)H dipolar interactions and allows to obtain amide proton line widths on the order of 20 Hz. Similarly, high-resolution proton spectra of aliphatic groups can be obtained if specifically labeled precursors for biosynthesis of methyl containing side chains are used, or if limited amounts of H(2)O in the bacterial growth medium is employed. This review summarizes recent spectroscopic developments to access structure and dynamics of biomacromolecules in the solid-state, and shows a number of applications to amyloid fibrils and membrane proteins.
AU  - Reif, B.
C1  - 7405
C2  - 29701
SP  - 1-12
TI  - Ultra-high resolution in MAS solid-state NMR of perdeuterated proteins: Implications for structure and dynamics.
JO  - J. Magn. Reson.
VL  - 216
PB  - Elsevier
PY  - 2012
SN  - 1090-7807
ER  - 

TY  - JOUR
AU  - Li, A.S.W.*
AU  - Cummings, K.B.*
AU  - Peter Roethling, H.*
AU  - Buettner, G.R.
AU  - Chignelq, C.F.*
C1  - 42725
C2  - 36379
SP  - 140-142
TI  - A spin-trapping database implemented on the IBM PC/AT.
JO  - J. Magn. Reson.
VL  - 79
IS  - 1
PY  - 1988
SN  - 1090-7807
ER  -