90 times

TALAM@BOOTES.UNM.EDU
Thu, 9 Dec 1993 10:09 MST

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NMR Users:
I was recently approached by R. Chapman from TPL inc. here in Albuqerque
They recently recieved a used Bruker Ac-300, and have sent back a 5mm bb probe
for repair several times due to what I would consider long 90 degree pulse
lengths - The latest times are given below

13C 18 us (90 degrees)
14N 90 us (90 degrees)

It is at the point that MR resources claims that these pulse lengths are
normal for this type of probe, and is hesitant about further repairs..

This strikes me as unaccurate concerning both of the AC250's here, operating
with 5mm bb probes gives

13C 4.1 us and 4.5 us (different instruments and probes)
O17 5.9 us and 6.2us
119Sn 7.5 us and 7.8us

Would anyone like to comment on the 90us 90degree pulse length listed above?
I am curious to know what is "typical"

Todd Alam
Dept. of Chemistry
University of new Mexico
Talam@bootes.unm.edu
505 277 4031

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