Feb 17, 2025
Version 1
Spin Echo with Whole-Echo Acquisition V.1
This protocol is a draft, published without a DOI.
- Alexander L. Paterson1
- 1National Magnetic Resonance Facility at Madison (NMRFAM), University of Wisconsin-Madison, Madison, WI, United States
Protocol Citation: Alexander L. Paterson 2025. Spin Echo with Whole-Echo Acquisition. protocols.io https://protocols.io/view/spin-echo-with-whole-echo-acquisition-dzcf72tnVersion created by NMRFAM Facility
License: This is an open access protocol distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: In development
We are still developing and optimizing this protocol, but it should be functional. We hope to solicit feedback primarily on clarity and usability. We intend to publish it in June 2025.
Created: January 21, 2025
Last Modified: February 17, 2025
Protocol Integer ID: 119911
Keywords: Materials Spin Echo: 23Na
Funders Acknowledgements:
National Science Foundation
Grant ID: 1946970
Abstract
Purpose
Acquisition of a Hahn-echo spectrum with whole-echo acquisition from a quadrupolar nucleus.
Scope
This protocol is part of a standard array of experiments to be run on a new sample. It can also be used as preparation for MQMAS experiments, particularly those involving split-t1 acquisition. This protocol can also be used when there is a significant probe or rotor background observed in the spectrum.
Guidelines
This sequence imposes a T2’ weighting factor on the intensities of the resonances; while typically negligible for short echo periods, this should be considered when using long echo periods.
When used for an integer spin nucleus, a solid echo (90°-90°) must be used instead of a Hahn echo (90°-180°).
Materials
Definitions:
- MQMAS: Multiple-quantum magic angle spinning
- MAS: Magic angle spinning
- CT: Central Transition
Before start
User should be familiar with the power limitations and duty cycle of the probe being used.
Expected amount of time SOP will use: 30 minutes.
Procedure
Procedure
Load the pulse program hahnecho.nmrfam.
Set pulse p1 and power plw1 to a central-transition-selective 90° pulse.
Note
If acquiring data on a spin-1/2 nucleus, ignore all references to central-transition selective and use a 90° pulse.
Set cnst2 to 2 to produce 180° CT-selective echo pulse, or to 1 to produce a 90° CT-selective echo pulse.
Note
If the observed nucleus is integer-spin, cnst2 must be set to 1.
Set the recycle delay, d1, to 1.3 × T1 if optimizing for sensitivity, or 5 × T1 if quantitative intensities are desired.
Note
Recall that the intensities are modulated by a T2’ weighting factor.
If collecting a MAS spectrum, set cnst31 to the MAS rate. If collecting a static, i.e., not spinning, spectrum, set cnst31 to 1e6.
Set the rotor period loop counter, l1, to an initial value of 1.
If the sample is static, set l1 to the desired echo delay in microseconds.
Set the pre-acquisition delay, d7, to 1 μ.
Note
This initial value will ensure that the whole echo is acquired, but might allow for residual FID to bleed through for small values of l1.
Set ns to a multiple of 16.
Acquire an initial spectrum.
Process the spectrum according to procedure for full-echo acquisition.
This involves setting a large first-order phase correction phc1.
Apodization can be applied using Gaussian, sine bell, or squared sine bell functions.
If half-echo acquisition is desired, left-shift the spectrum until the echo top is the beginning of the FID. With half-echo acquisition the large first-order phase correction phc1 is not required and exponential apodization can be used.
Increase l1 if necessary to either remove background signals or to prevent residual FID from the excitation pulse.
If removing background signal from the spectrum, increase l1 until the background is no longer observed.
If testing for MQMAS with split-t1 acquisition, increase l1 until residual FID is no longer overlaps with the whole echo.
Increase the number of scans, ns, to a value which will provide adequate signal-to-noise while respecting the phase cycle.
Acquire the optimized spectrum.
Protocol references
Duer, M. Solid-State NMR Spectroscopy: Principles and Applications; Blackwell Science: Malden, MA, 2002.
Protocol
NAME
Saturation Recovery
CREATED BY
NMRFAM Facility