Hi John
setting the sample temperature higher during the extended pumping time helps.
Once you start the cool down, not so much. By radiation and thermal conduction
there is some warming going into the probe and helps. Not to bake of impurities
but to increase the vapor pressure on some of them.
The burn in with a pulse sequence is IMHO a mixed bag. With good vacuum it
should not be needed. Sometimes one sees some artefacts in the FID's during
the first HSQC or HSQC-TOCSY that one runs. Those tend to disappear after
a while. If you do see this let this experiment run until the FID's are clean
and then start with your real experiments. If these artefacts come back
during the same cold period of the probe you might have a vacuum issue
going on.
Also do not burn in small diameter probes such as 1.7 mm cryoprobes.
Regards
Clemens
On 12/2/2025 3:29 PM, John H Grimes Jr. via groups.io wrote:
All,
For as long as I can remember, I'd been told that the way to cool off your
cryoprobe was to set the improve vacuum duration such that it pumps overnight,
heat the probe up to help bake off impurities, and then burn it in with an
appropriate pulse sequence the next morning when it is cold. As I was cooling
one down today, I actually thought about it and realized heating the probe is
not going to do anything as the coil is insulated from the sample portion so
it won't get warmed by turning up the temperature. So, is turning the sample
temperature up futile, or do I not understand the process correctly?
Thanks,
John
John Grimes | NMR Facility Manager
Complex Carbohydrate Research Center, University of Georgia
315 Riverbend Road
Athens, GA 30602-4712
(706) 542-4483
jgrimesjr_at_uga.edu<mailto:jgrimesjr_at_uga.edu>
--
==========================
==========================
====================
Clemens Anklin Ph.D. Vice President
Bruker BioSpin NMR Applications & Training
15 Fortune Drive NEW Phone: 978-313-5NMR(5667)
Billerica MA 01821 bluesky: _at_canklin.bsky.social
web: http://www.bruker.com
e-mail: clemens.anklin_at_bruker.com
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