13C observe with 2H decoupling

(and 1H decoupling)

uwz 12/12/02

This description addresses the case of performing the experiment without locking. Such experiments are useful for short-term acquisition (approx. 1 hour), but not for overnight experiments. Please come and talk to us, if you need to do overnight acquisition with 2H decoupling.

    Software setup:

    In the acqi window (locking window)

  1. Turn off the lock
  2. Set the lock power to 0

    3. In the setup window

  3. Set up a 2H experiment (Setup à 2H à solvent). Do not run the experiment (The hardware is not set up for it!)
  4. Write down the tof value.

    5. Hardware setup:

  5. Remove filter from lock port (long gray tube attached to front side of "Magnet Console Interface Box").
  6. Terminate the connector from which you removed the filter with a 50 W terminator (from top of console).
  7. Remove the big black terminator from the cable labeled "Console Output #3".
  8. Attach the lock filter to "Console Output #3", by using a suitable converter plug from the top of console
  9. Insert 13C band pass filter (from cardboard box labeled "Bandpass 98-120 MHz) between the probe X-channel and the X-filter box using any additional cable.

    10. More software setup:

  10. Setup standard 13C parameters.
  11. Type dn2=’H2’ dpwr2=35 dm2=’nny’ dmm2=’w’ homo2=’n’ dmf2=4500 dof2=(tof value from step 4) from the deuterium setup.
  12. (only if proton decoupling is NOT wanted, type dm=’n’).

You may have to adjust the dpwr2 value to a sufficient decoupling value. On a test sample (for example the standard CDCl3/Toluene sample) you can test the decoupling efficiency by typing array('dpwr2',8,5,5). Do not set dpwr2 above 40 dB. If you still have trouble, ask the staff to help you take a deuterium NMR spectrum to determine your dof2 precisely. The instrument needs to be recabled, so do not attempt this on your own!

When you are done, you have to set the instrument back to standard conditions!

Here is how to:

  1. Terminate the cable labeled "Console Output #3" with the big black terminator.
  2. Connect the lock filter back to the lock output in front of the "Magnet Console Interface Box".
  3. Take out the 13C filter and place it back into the cardboard box.
  4. Deposit all extra electronics back onto the spectrometer console.
  5. Finally, check that you can lock and take a regular 13C spectrum, for example on the standard sample (set it up new and use nt=4)