Administration and Maintenance

This information is primarily for the system administrator. You must be logged in as vnmr1 for most administrative tasks.


The system administrator should periodically (every couple of months) adjust shims to obtain lineshape specifications
  • insert Varian’s lineshape standard sample
  • tube probe and lock as usual; lock power should be about 20 or less
  • load in previously saved lineshape fid to retrieve the proper parameters
  • either start from current shims, or used those from above file by typing “load=‘y’ su”
  • manually adjust low-order Z shims
  • perform gradient shimming using H2_map shimmap
  • carefully adjust the low-order non spinning shims (e.g., X1, Y1, XZ, YZ, XY, ZXY)
  • display spectrum to view lineshape
  • to quantify quality of lineshape, position cursor on line and type “res”
  • repeat as needed
  • save data in vnmr1/vnmrsys/data/lineshape directory, using date as part of file name
  • enter lineshape specs in spectrometer logbook

Cryogens - Nitrogen

  • N2 should be replenished once a week (500 can go 2 weeks if necessary)
  • for best data, do not collect data during N2 fill
  • data collection can resume immediately after N2 fill

Cryogens - Helium

  • 800 needs He about every 4 weeks
  • 500 needs He every 3rd time the 800 is done (1st fill 500, remainder into 800)
  • do not collect data during He fill
  • 500 - can resume data collection immediately after He fill
  • 800 - should wait 24 hours before collecting data