Hi Everyone:
I have been running more and more DOSY experiments here these days and
subsequently have been wondering more and more about the absolute value of
the gradient strengths delivered to the sample. The spectrometer I am using
is a Bruker AV-500 with z-gradients only (GAB amplifier). I am aware of the
calibration value of 5.35 G/cmA for Bruker z-Gradient probes and the storage
of the constant in the file gradient_calib in <home>/conf/instr. I am
thinking it would be a useful exercise to experimentally verify this number,
not only to ensure the accuracy of diffusion measurements but also as a
benchmark to use down the road if we experience gradient hardware problems.
And furthermore.I would simply like to know how to do it!
I would love to hear from those of you who have calibrated gradient
strengths. I am particularly interested in the sample that you used. I do
not have at my disposal Shigemi tubes and have no experience with limited
sample volumes. I have read on occasion about phantom samples used for this
purpose. How are these samples prepared in terms of material used, placement
of the plug etc? Do you just use normal (tap) water? Are trapped bubbles a
concern? If so, how best to avoid?
Thanks for any info.and of course if there is interest I will post a
summary.
Cheers!
Mike
P.S. Does anyone know the reason why in the gradient_calib file there is the
number 5.35 but then below that there are three more lines, each with 1.0?
In other words, my file looks like:
5.35
1.0
1.0
1.0
----------------------------------------------------------------------------
----------
Michael D. Lumsden, Ph.D.
NMR Facility Coordinator
Room 428, Atlantic Region Magnetic Resonance Centre
Department of Chemistry, Dalhousie University
Halifax, Nova Scotia, Canada
B3H 4J3
phone: 902-494-1635
FAX: 902-494-1310
http://armrc.chemistry.dal.ca
This archive was generated by hypermail 2b29 : Wed Dec 27 2006 - 01:02:08 PST