Performing VT experiments on 500MHz DMX spectrometer.

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 the VT nitrogen gas is hooked up to the glass Dewar in the probe and that
   gas is flowing. The glass Dewar is very fragile, please take extremely cautions while
   working with it. The flow rate should be ~500 l/h.
* Turn “ON” the VT controller on spectrometer’s console.
* While in xwinnmr software type ‘ EDTE ’ command and EDTE main window appears.
* Make sure that target sample temperature is set up to room temperature.
* Using EDTE menu set the maximum heater power to 15%. It is rather rare that a higher
   value will be needed.
* 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 turn the heater button ‘ON’. The
   button is placed on the spectrometer’s console. Another heater button “ON/OFF” that is
   placed in the EDTE menu is not designed to work.
* Wait until sample temperature is close to target and increase it another 5 degrees.
* To get to the final required temperature, proceed in the steps of no more than 5 degrees to
   avoid thermal and current shock in the hardware.
* When the temperature has been achieved wait a certain period of time before you start to
   perform NMR experiment to equalize the temperature across the sample. A 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 5degree 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 pushing the button heater “ Off” on VT controller.
* 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 laboratory.

The case of lower than ambient temperature
home