pseudo 2D direct detection CPMG hahnecho; relaxation experiment

This is an inversion recovery experiment to measure direct detection T2 The experiment is pseudo 2D. This is NYSBC standard data set and pulse program for 1H-13C cross polarization with rotor synchronized 13C hahnecho followed by 13C acquisition with 1H decoupling. The pulse program has power safety limitations specific for the particular probe. The pulse program hahnecho2D_3.2EF750.nysbc, ramp shape file tancn_100_SCALE and include file power_intro.incl are located in the dataset directory.

Citation

Sample heating

To minimized heating of conductive samples, we recommend using an Efree/lowE probe. However, a combination of frictional heating from spinning and RF heating on long pulses on both channel may cause substantial sample heating and temperature gradient across the sample even in an Efree probe. The heating may damage the sample. The heating and temperature gradient across the rotor may substantially compromise the precision of measurements and data fitting.

Citation

[https://www.ncbi.nlm.nih.gov/pubmed/10868566?dopt=Abstract] Heating of samples induced by fast magic-angle spinning, Brus, J., Solid State Nucl. Magn. Reson. 16, 151–160 (2000).

[https://onlinelibrary.wiley.com/doi/abs/10.1002/mrc.4450] Heating and temperature gradients of lipid bilayer samples induced by RF irradiation in MAS solid-state NMR experiments, Wang, J., Zhang, Z., Zhao, W., Wang, L. & Yang, J., Magn. Reson. Chem. 54, 753–759 (2016).

[https://www.biorxiv.org/content/10.1101/566729v1.full] TmDOTP : An NMR- based Thermometer for Magic Angle Spinning NMR Experiments Dongyu Zhang, Boris Itin, Ann E. McDermott; preprinted

Probe and power limitations

R1ρ experiments require long simultaneous medium to high power pulses on 1H and X channels. Make sure that you don't exceed the maximum allowed powers/lengths and damage the probe. When in doubt, contact the manufacturer.

Protocol

Make sure that recycle delay is longer than 3xT1

Samples

The experiments were performed with crystallized u-15N,13C-labeled-N-acetyl-valine

Processing and analysis

Fourier transform a pseudo-2D experiment in the direct dimension, measure the peak intensities as a function of length of the spin locking pulse and use a monoexponential function to obtain T1 values

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Pulse Sequence and Parameter Set