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High Field NMR - Training

Hardware Setup

The NMR hardware needs to be ready for NMR experiments. The routine operation procedure for this is (1) Preparing a NMR sample and inserting it in the magnet, (2) Controlling the sample temperature, (3) Making the magnet field locked, (4) Optimizing shims, and (5) Tuning the probe. Generally these steps are required whenever samples are exchanged.

Hardware SetupBruker Procedure
Sample Preparation
  • The NMR sample height is 4 cm for Bruker.
  • The sample height of the Shigemi tube includes the length of the glass block.
  • Never use Varian Shigemi tubes in Bruker NMR.
  • Measure the sample depth always and correctly.
  • Please be aware of the eject air bleeding when changing samples in the magnet.
sample bruker

Variable Temperature (VT) Control
vt control
  • The cooling air is supplied through optional chillers (FTS or BCU-Xtreme)
  • The probe has a heater for heating air.
  • Temperature is measured by a thermocouple inside probe.
  • Caution; Never turn off the air flow.
edte; for temperature control
bruker vt
Do not readjust Probe Heater max. and Gas flow.

BCU-Xtreme; the optional chiller
BCU Xtreme
When cryoprobe is in use at temperature higher than 35 °C, please turn off BCU-Xtreme.

Locking B0 (the Magnetic Field)

Locking is to stabilize B0 time to time. When locking is activated, the feedback-control of B0 is achieved by reading the 2H signal and adjusting the Z0 shim.

lock; for automatic locking
lockdisp; to display the lock in the large window
bruker locking
bsmsdisp; to control locking and shimming manually
bruker bsmsdisp
The lock signal can be controlled manually by adjusting Phase, Power, Gain, and Field (with lock off). The Field parameter is Z0.

Shimming B0 (the Magnetic Field)

Shimming is to homogenize B0 in the sample space. Bio-NMR uses about 40 different shims to achieve this goal. The main shim sets that users must check are Z1, Z2, Z3, Z4, X1, Y1, XZ, and YZ.
shimming Z-gradient shimming optimizes z shims (up to Z6).
rsh; to read and set shim values
topshim; Gradient shimming automatically
topshim gui; topshim with the interactive window (options: before / after, shigemi, z6)
topshim gui
Main shim sets on bsmsdisp bruker shims

Tuning Probe
Probe is used to excite and receive NMR signals. If miss-tuned, longer pw90 and lower sensitivity are resulted. Before tuning the probe, setting up RF channels is required (see Experiment Setup).
probe tuning
atmm; Automatic tuning with manual motor controls
atma; fully automated tuning
wobb; for manual tuning
bruker tuning
bruker atmm

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