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Applications
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Figure 6.3: Overlay of NOESY-HSQC (blue), TOCSY-HSQC (orange) and CPMG-HSQC (green) spectra
of 0.5mM ubiquitin in 95:5% H2O/D2O measured at 800MHz TCI CP.
In the figure above the left side shows the NMR Thermometer disabled (monitoring mode)
and the right side the NMR Thermometer enabled (regulation mode).
Heating caused by Spinning Speed (HR-MAS)
Figure 6.4: 1H NMR spectra on a liver sample with sodium acetate added.
In the figure above, different spinning speeds were used (1, 2, 4, 6 and 8 kHz). Left part:
NMR Thermometer disabled (monitoring mode); Right part: NMR Thermometer enabled
(regulation mode).
An interesting application of the NMR Thermometer is high resolution MAS on biological
material. Depending on the spinning speed used in HR-MAS (1 to 8 kHz) the frictional
heating in the rotor is different and hence the temperature varies. To compensate for the
heating is not only of interest for the comparability of the spectra, but it is also important in
order to preserve sensitive sample material (like tissue material). The temperature difference
between sample and probe sensor can be as much as 5K in the case of 8 kHz spinning
speed.
Applying a spin lock sequence (TOCSY) on top of that could increase the temperature even
further. Both heating effects can be compensated for by the NMR Thermometer:
6.2.2