Dear Rajan
I have to start with apologizing to you and everyone else who has looked at
the sequence. This is not a watergate this is a venerable jump-return echo
(just as the name suggests "jr" and "se'). It looks like some comments come
from somewhere else.
These jump-return or 1-1 or more correctly 1-1bar experiments and the
corresponding echo ones can be run without gradients. The are mostly applied
in the nucleic acid world where they let you get beautiful spectra of the
rapidly exchanging species imino protons. The simplest can be found as "p11"
Gradients clean up what you used to remove by careful adjustment of parameters.
The parameters to adjust are the duration of the second pulse. Usually= a
fraction of a microsecond shorter than the first one. and either the phase
of the second pulse or the carrier frequency. The phase or frequency adjustment
corrects for a bit of precession of the water during d19. The duration of
the second pulse for relaxation or radiation damping during that same delay.
To be able to correct the phase of the second pul you should modify the
sequence with this :r after ph2. The correction is then entered as phcor2.
Again small steps, fraction of a degree.
d19
p0 ph2:r
go=2 ph31
You can adjust both p0 and phcor2 in GS and see the water signal getting smaller.
In a similar way you change these parameter pluse the phase of the 4th pulse to
optimize the suppression in the echo sequence.
With best regards
Clemens
On 2/16/2024 2:06 PM, DrSpin wrote:
Dear Spinners
In the outset, due apologies if I am transmitting a silly question through
this venerable platform and taking up your time. As this is the last water
hole in the Savannah to turn to when it comes to our trade, I am nevertheless
hazarding this query.
I have an old system i.e. AV-I operating at 200 MHz (old by today's standards,
surely) coupled with an older probehead that doesn't have a gradient coil.
This is a busily used instrument in the teaching lab, initiating the young
undergrad Padawans to the wonders of magnetic resonance and show them the
way to become Jedi Knights (gulp !).
The problem: What I need to solve is to suppress the rather large water peak
in one type of samples with anything other than the presat technique. As a
benchmark, I used Bruker stock pulse program "zggpjrse" and it gives beautiful
results in a system with gradients.
I modified this program "zggpjrse" i.e. by removing the gradients, and I get
results with limited success.
Since the gradients seem to play such a crucial role, I wanted to explore any
possible options. I have noticed this SMB connector in the SCB boards of this
vintage that is marked as 'homospoil start'.
Question: Do any of you know/recall the way we can use an input trigger to
the SCB to initiate a spoil gradient from within the pulse program and use
this as the poor person's way of generating a large enough Z-gradient using
the shim stack, which should be adequate in a simple 1D implementation like
the one I am envisaging ?
If I am not mistaken, old timers in the group probably played with the homospoil
feature to tame solvent peaks like this before probes with gradient coils became
a given.
thank your for your valuable time.
Best
Rajan
--
____________________________________
Rajan K Paranji, Ph.D. NMR Services Manager Department of Chemistry Room 65,
Bagley Hall University of Washington Seattle, WA 98195 phone : 206 685 2581
fax: 206 685 8665 email: rajanp_at_uw.edu
_____________________________________
--
==========================
==========================
====================
Clemens Anklin Ph.D. Vice President
Bruker BioSpin NMR Applications & Training
15 Fortune Drive NEW Phone: 978-313-5NMR(5667)
Billerica MA 01821 twitter: _at_canklin
web: http://www.bruker.com
e-mail: clemens.anklin_at_bruker.com
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Received on Sat Feb 17 2024 - 07:32:32 MST