Hi Serge,
Seconding Ronald and Igor's suggestions. Should the specific pulse program
not matter so much at this stage you might also try one of the MLEV variants.
If it still doesn't work when using a cookie-cutter parameter set and pulling
powerlevels with 'getprosol' then I'd revisit my 90 pulse widths and consider
calibrating to a lower power level.
For power related problems in a tocsy my first thought goes to the spin-lock.
If truly desperate and willing to cut corners I would shorten the duration
slightly from 80ms to ~60-70ms. It might let data collection proceed and
only takes a minute or two to find out. Final quality would probably suffer,
but sometimes unoptimized data is preferable to no data. Powercheck seems
operational so I wouldn't expect any additional risk to the probe.
As for why hsqc-tocsy worked...tough to guess without having been there.
Especially if the tocsy was setup using a similar strategy. There are a
few extra deltas that make it a slightly longer sequence than tocsy, though
only a few milliseconds in total. If the combination of powers, durations,
and duty cycling were at the edge of the powercheck threshold then maybe
it just barely made the cutoff.
Kind regards,
Luke
Luke Fulton, PhD
CHEM BLDG R003
NMR Core Facility Director
Unit 3060
COR2E & Department of Chemistry
55 N Eagleville Road
University of Connecticut
Storrs, CT 06279
email: fko24003_at_uconn.edu
(alias): luke.fulton_at_uconn.edu
mobile: (603) 953-5275
________________________________
> From: main_at_ammrl.groups.io on behalf of serge_lavoie via groups.io
> Sent: Thursday, July 24, 2025 9:58 AM
> To: main_at_ammrl.groups.io <main_at_ammrl.groups.io>
> Subject: [AMMRL] a simple 2D TOCSY on a bruker cryoprobe
Hi all,
I am trying to record a basic 2D TOCSY experiment with our instrument (Bruker
Neo 500 MHz, cryoprobe prodigy BBO). For a reason i dont understand, it fails
after a few dummy scan with this error message: 'EMERGENCY-STOP activated: Peak
power limit exceeded, EmStop activated...'. I have verified that the probe was
correctly tuned and matched. I have checked that all pulse length and power are
set according to the pulse program instruction. Here a the most important
parameter i used:
* pulprog: dipsi2gpphzs
* td = 4096 x 256
* ds = 16, ns = 8
* d1 = 2 s; d9 = 80 ms
* sw = 2778 x 2778 Hz; o1p = 3.25 ppm
* p1 = 10 µs, p6 = 30 µs, p32 = 20 ms
* pldb1 = -11.92 db; pldb10 = -2.3807 db; spdb29 = 12.26 db
Note that using the same instrument, i successfully recorded 1H, 13C, hsqc,
hmbc, dqf-cosy, even hsqc-tocsy experiments. What is wrong with 2d tocsy?
Serge Lavoie
Université du Québec à Chicoutimi
Saguenay (Québec)
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Received on Thu Jul 24 2025 - 10:47:07 MST