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Related Concept Videos

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Double resonance techniques in Nuclear Magnetic Resonance (NMR) spectroscopy involve the simultaneous application of two different frequencies or radiofrequency pulses to manipulate and observe two distinct nuclear spins. One important application of double resonance is spin decoupling, which selectively suppresses coupling with one type of nucleus while observing the NMR signal from another nucleus, simplifying the spectrum and enhancing resolution.
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Related Experiment Video

Updated: Jun 4, 2026

15N CPMG Relaxation Dispersion for the Investigation of Protein Conformational Dynamics on the µs-ms Timescale
08:09

15N CPMG Relaxation Dispersion for the Investigation of Protein Conformational Dynamics on the µs-ms Timescale

Published on: April 19, 2021

Exact solution of the CPMG pulse sequence with phase variation down the echo train: application to R₂ measurements.

Alex D Bain1, Christopher Kumar Anand, Zhenghua Nie

  • 1Department of Chemistry and Chemical Biology, McMaster University, Canada. bain@mcmaster.ca

Journal of Magnetic Resonance (San Diego, Calif. : 1997)
|February 15, 2011
PubMed
Summary

This study presents an exact algebraic solution for Carr-Purcell-Meiboom-Gill (CPMG) experiments, improving R₂ measurements by reducing errors from frequency offsets and field inhomogeneity. Phase variation techniques significantly enhance accuracy, extending reliable offset ranges.

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Last Updated: Jun 4, 2026

15N CPMG Relaxation Dispersion for the Investigation of Protein Conformational Dynamics on the µs-ms Timescale
08:09

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Published on: April 19, 2021

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Published on: November 1, 2024

Area of Science:

  • Magnetic Resonance Spectroscopy
  • Nuclear Magnetic Resonance (NMR)

Background:

  • Carr-Purcell-Meiboom-Gill (CPMG) experiments are susceptible to errors in R₂ measurements.
  • Frequency offsets and pulse imperfections can cause oscillations and inaccurate decay rates.

Purpose of the Study:

  • To develop and apply an exact algebraic solution for CPMG experiments.
  • To explore approximate solutions for understanding oscillations and effective decay rates.
  • To propose an optimization model for quantifying CPMG intensity oscillations.

Main Methods:

  • Implicit exact algebraic solution for CPMG experiments.
  • Approximate solutions to analyze oscillations and effective decay rates.
  • Effective field approximation and dimensionless variables for an optimization model.
  • Development of a second-order expression for effective R₂ with phase variation.

Main Results:

  • Exact CPMG calculations eliminate systematic R₂ errors from frequency offsets.
  • Group phase variation in CPMG experiments reduces oscillations and field inhomogeneity effects.
  • A second-order expression provides reliable R₂ estimates within ±½γB₁ with phase variation.
  • An advanced optimization model extends reliable R₂ estimation to ±γB₁ with phase variation.

Conclusions:

  • The exact algebraic solution and phase variation are crucial for accurate R₂ measurements in CPMG experiments.
  • The proposed optimization model significantly broadens the applicability of CPMG NMR spectroscopy.
  • These advancements improve the reliability and accuracy of NMR relaxation time measurements.