CryoProbe User Manual BRUKER 55 (107)
Recommended NMR
parameters 5
5000000
General 5.1
0
When running a long experiment with extensive decoupling or spin-lock, check
the progress of the acquisition during the first few minutes after its start. In case of
excessive heating the NMR coil assembly with RF, the system will send error
messages and might automatically halt the experiment or even warm-up the Cry-
oProbe if its warnings have been ignored (see also "Sample temperature con-
trol" on page 55).
Samples and spinners 5.2
0
The following B
RUKER spinner types were tested so far:
opaque white recommended
blue ok
ceramic not approved
Use only high quality sample tubes with high axial symmetry. Susceptibility-com-
pensated tubes (e.g. Shigemi) are recommended. In the worst case, however, a
bad sample tube just cannot be spun.
Observe the limits pertaining to the sample parameters as given on the L
IMITA-
TIONS - WARNINGS sheet for each individual CryoProbe such as
max. sample diameter,
sample depth limits,
min. VT gas flow rate,
recommended filling height.
Filling the sample tube above the recommended height will neither increase the
signal-to-noise nor improve the shimming, but it will deteriorate the precision of
the sample temperature control.
Sample temperature control 5.3
0
Although the CryoProbe has an excellent thermal insulation between the sample
space and the cold RF coils, a small thermal radiation is constantly cooling the
sample. A sufficient VT gas flow is crucial to avoid temperature gradients in the
sample. The higher the VT gas flow, the smaller the temperature gradient. Unlike
conventional probes, a VT gas flow as high as possible is preferred in a Cryo-
Probe, i.e. the VT gas may almost lift the sample. See the ‘L
IMITATIONS - WARN-
To Next Page
Loading...
Need help?
General
