MAS Tubing Connections
User Manual Version 002 BRUKER BIOSPIN 27 (327)
The following gas requirements exist:
1. At room temperature or higher: dew point min. -30 °C, compressed air will do.
2. At temperatures 200 °C or higher (suitable probe required!): nitrogen is re-
quired to prevent coil oxidation.
3. At temperatures between room temperature and -50 °C (using a B-CUX cryo
cooler with -80 °C exchanger temperature): nitrogen or compressed air with a
dew point ≤ -100 °C.
4. At temperatures below -50 °C (using liquid nitrogen and heat exchanger): boil-
off nitrogen with a dew point -196 °C.
Any compressed gas used in NMR probes must be free of any liquid droplets or of
oil (from compressor lubrication). Especially oil (even smallest amounts) will lead
to probe arcing, and/or spinning problems and potentially expensive repair. Using
boil-off nitrogen should be carefully considered, since it is by far the most reliable,
stable and trouble free source of compressed gas, to be used at any temperature!
Connections 3.5.1
MAS tubing connections are quite different between different types of probes (for
stationary, non spinning probes, only frame flush and VT gas are required:
1. WB probes, VTN, WVT and DVT probes (VTN: VT-normal range, WVT: VT-
wide range). These probes have a diameter of 72 mm and are longer than SB
probes. Probe lengths are the same up to 400 MHz, the same for 500 and 600
MHz, and longer for higher fields.
2. SB probes, VTN and DVT type probes, also major differences between older
and more modern probes. Furthermore, probes with sample insert/eject and
probes without insert/eject exist.
The major difference between DVT and VTN/WVT probes is that for VTN/WVT
probes the bearing gas is used for temperature control, whereas for DVT probes,
bearing, drive and VT gas are separate.
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