Related Experiment Video
Updated: Jun 24, 2026

15N CPMG Relaxation Dispersion for the Investigation of Protein Conformational Dynamics on the µs-ms Timescale
Published on: April 19, 2021
Improved pulse sequences for measurement of small long-range couplings between heteronuclei (29Si-13C) at natural
Vratislav Blechta1, Jan Schraml
1Institute of Chemical Process Fundamentals of the ASCR, v. v. i., Rozvojová 135, CZ-165 02 Prague 6-Suchdol, Czech Republic. Blechta@icpf.cas.cz
Abstract:
The gradient pulse sequences for measurement of small long-range couplings between heteronuclei ((29)Si-(13)C) in natural abundance reported to date (INEPT-(Si,C)gCOSY and INEPT-(Si,C,Si)HMQC) suffer from significant signal loss when these nuclei ((29)Si, (13)C) are coupled through one-bond couplings to protons. This negative effect can be completely eliminated by using non-gradient versions (INEPT-(Si,C)COSY) or by switching proton decoupling off during gradient pulses (modified INEPT-(Si,C,Si)gHMQC pulse sequence). The beneficial effects of these two approaches on the quality of the spectra are demonstrated here.
Related Concept Videos
¹³C NMR: ¹H–¹³C Decoupling
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
2D NMR: Overview of Homonuclear Correlation Techniques
COSY90 is the standard two-dimensional (2D) COSY experiment that...
¹H NMR: Interpreting Distorted and Overlapping Signals
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
NMR Spectrometers: Radiofrequency Pulses and Pulse Sequences
Double Resonance Techniques: Overview
Spin decoupling is usually achieved by...
Other Nuclides: 31P, 19F, 15N NMR
While fluorine-19 and phosphorous-31 have high natural abundances (100%) and positive gyromagnetic ratios, nitrogen-15 has a low natural abundance and a negative gyromagnetic ratio. However, nitrogen-15 is still preferred over nitrogen-14 (which has a high...

