TUNING & MATCHING...
When tuning 1H...
If the dip is shifted off screen with a 10.0 MHz wobb-sw and
no part of it crosses the center line, TWO PERSON tuning/matching
IS REQUIRED on the DMX750 and DRX800. One person should be watching
the monitor, the other tuning.
Use a minimum wobble spectral width of 10 MHz on the 750 and 800.
If you do not see a dip close to center, open the spectral width
to 20 MHz and look again BEFORE you start turning the rod.
Turn the screwdrivers slowly (~1/4 turn at a time). IF YOU FEEL THE
RESISTANCE INCREASE, STOP turning the rod. When in doubt, DON'T keep
turning. Get help.
Tuning 13C/15N...
DON'T ATTEMPT TO TUNE AND MATCH THE X nuclei (13C/15N) on the triple resonance
probes. There is only a minute amount of variance between samples for
Bruker probes. You SHOULD NOT TOUCH tune and match for these nuclei on
any of the shared instruments (DRX800, DMX750, DMX600, DMX500, DMX499).
If you feel that tune/match needs adjustment, speak with Dusty, Ad or Marius.
1H pw's on the DMX750 and DRX800:
Don't set the power for hard 1H pw's lower than 0 dB...
A pw between 8-12us is sufficient. If you have a high
salt sample AND your pw exceeds 12u at 0 dB, use -1 or -2 dB.
Do not use powers higher than -2.
13C 90's and 15N 90's:
The highest power/shortest pw that you can safely use for a
given instrument and probe is posted in the notebook by the
spectrometer. DO NOT USE HIGHER POWERS than those posted.
You risk arcing and arcing IRREVERSIBLY DAMAGES THE PROBE.
13C Decoupling:
If you are decoupling 13C with GARP during acquisition, make sure
that you use NO LESS than a 60us 90 degree pw for the lower field
instruments (500,600 MHz) and NO LESS than a 55us 90 degree
pw for the higher field instruments (750,800).
When decoupling 13C during acquisition, your acquisition time (AQ)
SHOULD NOT EXCEED 55ms.
13C SPIN LOCKS (HCCONH, CCONH, etc)
For sequences using DIPSI decoupling for 13C spin-locks, the
following parameters are acceptable at 750 MHz and 800 MHz:
30 microsecond 90 degree 13C pw
NO MORE THAN 3 dipsi loops ( duration must be <=23 millseconds)
Relaxation delay between scans must be >= 2 seconds!
15N Decoupling
When decoupling 15N during acquisition, make sure that you
use NO LESS than a 200us 90 degree pw for the lower field
instruments (500,600 MHz) and NO LESS than a 185us 90 degree
pw for the higher field instruments (750,800).
When decoupling 15N during acquisition, your acquisition time (AQ)
SHOULD NOT EXCEED 75ms.