Performing VT experiments using 400MHz DRX spectrometers
The case of higher than ambient temperature
* Use the proper spinner turbine for VT experiments. Actually, the
gray fiber glass spinners
are design for VT experiments.
* Make sure that VT nitrogen gas is hook up to the glass Dewar
in the probe and the flow
takes place. The glass Dewar is very fragile, please
take extremely cautions while
working with it.
* While in xwinnmr software type ‘EDTE
’ command and EDTE main window appears.
* Make sure that target sample temperature is set up to room
* Set maximum heater power to 15%
. It is rather rare that higher value will be needed.
Turn heater “ON”
* Make sure that your target temperature does not exceed the
limit of the probe
specifications. Exceeding the probe’s limit temperature
will damage the probe. Magnet
might also be damaged.
* Set the temperature 5 degree
higher than present and click the "APPLY" "
OK " button
* Wait until sample temperature will be close to target and increase
it for another 5 degree.
* To get to the final required temperature, proceed in the steps
of no more than 5-8 degree
to avoid thermal and current shock in the hardware.
* While in the required temperature wait certain period of time
before you start to perform
NMR experiment to equalize the temperature across
the sample. The 20 –30 minute
period of time is usually needed. However, you
may like to find out your own waiting
time for temperature equalization.
* After experiment is finished, decrease the temperature in
the 5-8 degree intervals until the
room temperature is achieved. Never introduce the
thermal shock to the system by
changing the temperature with too large intervals.
* Turn off the heater by clicking heater button “
Off” in the EDTE menu.
* Exit the EDTE menu.
* To cool down probe’s electronic and shims to the ambient conditions
an additional time
between 30–120 minutes
is needed. This depend on how long experiment took place and
what was the final temperature. Mark your VT experiment
in logbook so a next user will
be aware about previous conditions. Consider those
limitation while signing up so the
sign up policy will be obeyed.
*To find out more details, please refer to the Bruker manual
that is available in NMR
The case of lower than ambient temperature