Hi Serge
The maximum duty cycle demand is from the DIPSI sequence of this pulse
program. You are using -2.38 dB, which is about 1/4th of the peak power
you use for your hard pulse. So, at 80 ms pulse train, this will put the
max demand on your probe limit. Can you tweak the p6 to be a bit 'softer'
(p6 is the soft 90 pulse from which the entire DIPSI is derived) ? Your SW
is about 5.2 ppm (?) and so you may not need a robust p6 pulse. You are
using 30 us and even as a soft 90 pulse, you have an excitation bandwidth
of 8330 Hz for this pulse. DIPSI typically provides about 2.2 times that
bandwidth coverage. So, you can afford to go further down in p6.
Even if you went down to 40 us, your rectangular pulse bandwidth is 6249
Hz. With DIPSI, this should give you needed coverage of 2778 Hz
comfortably.
Best Wishes
Rajan
On Thu, Jul 24, 2025 at 7:48 AM D'Anciaes Almeida Silva, Igor via groups.io wrote:
> Hi Serge,
>
> I'd start checking the peak powers for the nuclei involved at "edprobe".
> Maybe the ones at the pulse sequence are higher then what its written there.
>
> Best,
>
> ----------------
> Dr. Igor d'Anciães Almeida Silva
> Research Scientist - NMR Core
> University of Missouri-Columbia
> 32A Chemistry Building
> ------------------------------
> *From:* main_at_ammrl.groups.io <main_at_ammrl.groups.io> on behalf of
> serge_lavoie via groups.io <serge_lavoie=uqac.ca_at_groups.io>
> *Sent:* Thursday, July 24, 2025 8:58 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 - 10:47:43 MST