Jul 30, 2025
Version 3
Quantitative Bloch Decay for Spin-1/2 Nuclei V.3
- Alexander L. Paterson1
- 1National Magnetic Resonance Facility at Madison (NMRFAM), University of Wisconsin-Madison, Madison, WI, United States
Protocol Citation: Alexander L. Paterson 2025. Quantitative Bloch Decay for Spin-1/2 Nuclei. protocols.io https://dx.doi.org/10.17504/protocols.io.261ge5r7yg47/v3Version 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: Working
We use this protocol and it's working
Created: June 25, 2025
Last Modified: July 30, 2025
Protocol Integer ID: 221033
Keywords: Quantitative MAS Bloch Decay: Spin-1/2, 1d nmr spectra, acquisition of 1d nmr spectra, quantitative bloch decay, t1 relaxation of each resonance, d1 relaxation period, 1d mas spectrum, nucleus with quantitative intensity, t1 relaxation, nmr, nuclei, nucleus, spectra, spectrum, resonance
Funders Acknowledgements:
National Science Foundation
Grant ID: 1946970
Abstract
Purpose
To acquire a 1D MAS spectrum of a spin-1/2 nucleus with quantitative intensities.
Scope
The acquisition of 1D NMR spectra of spin-1/2 nuclei with quantitative relative intensities requires attention to be paid to the T1 relaxation of each resonance. This SOP should only be followed when quantitative relative intensities are required. If only lineshapes or chemical shifts are required, the d1 relaxation period can be reduced in duration.
Guidelines
If there is a significant rotor or probe background, an echo sequence may be more appropriate.
The quantitative intensities described here are relative intensities, not absolute intensities. Determining absolute intensities, sometimes known as spin counting, is outside the scope of this SOP.
Materials
Definitions:
- T1: Longitudinal relaxation time constant
Troubleshooting
Safety warnings
High-power decoupling can cause damage to a probe if applied incorrectly. Ensure that the decoupling power and duration are set within safe limits.
Before start
User should be familiar with the power limitations and duty cycle of the probe being used.
User should be familiar with the maximum safe spinning speed of the probe and rotor being used.
Accurate T1 relaxation times and calibrated pulse lengths must have been obtained prior to starting.
The expected amount of time to completion is highly sample-dependent and cannot be accurately estimated ahead of time.
Procedure
Load pulse sequence hpdec.
Set the relaxation time d1 to 5 × T1, where T1 is the largest value previously measured.
Set the pulse length p1 and pulse power plw1 to a previously optimized 90° pulse.
Set the 1H decoupling program, CPDPRG2, pulse length, PCPD2, and pulse power, plw12, to a previously optimized 1H decoupling condition.
If no 1H decoupling is required, set the pulse power plw12 to 0 W.
Set the acquisition time aq to a sufficiently long value such that the FID is not truncated, but less than 50 ms if decoupling is used.
Safety information
Applying high-power decoupling for more than 50 ms can cause physical damage to the probe.
Safety information
Ensure that the relaxation time d1 is long enough to respect the duty cycle of the probe. This typically requires d1 to be at least 20x longer than aq.
Adjust ns to effectively make use of available experimental time while achieving sufficient signal-to-noise ratios.
Note
If a good number for ns cannot be estimated, spectra can be acquired in blocks and added via fidsum.
Process the spectrum while paying careful attention to background subtraction and baseline correction if necessary.
Obtain the relative intensities of the resonances via integration if well-resolved, or deconvolution if not.
Protocol references
Y. Nishiyama and N. T. Duong, “Practical guides for 1H detected solid-state NMR under fast MAS for small molecules,” Journal of Magnetic Resonance Open, vol. 10-11, p. 100062, Jun. 2022.
https://doi.org/10.1016/j.jmro.2022.100062
Example Data at 1.1 GHz: usnan.org/ark:/83454/e1d5056070-adc9-42a0-8c4c-0dd64ea732d4
Example Data at 900 MHz: usnan.org/ark:/83454/e1dee19c5b-b543-42d6-a01d-3f8e3dd3856d
Example Data at 600 MHz: usnan.org/ark:/83454/e18ed3ed7b-c9d3-4afa-8ce0-d1664b865868