Format

Send to

Choose Destination
Solid State Nucl Magn Reson. 2015 Nov;72:104-17. doi: 10.1016/j.ssnmr.2015.09.003. Epub 2015 Sep 9.

Solid-state NMR indirect detection of nuclei experiencing large anisotropic interactions using spinning sideband-selective pulses.

Author information

1
UCCS, CNRS, UMR 8181, University of Lille, Villeneuve d'Ascq 59652, France; Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China.
2
UCCS, CNRS, UMR 8181, University of Lille, Villeneuve d'Ascq 59652, France.
3
UCCS, CNRS, UMR 8181, University of Lille, Villeneuve d'Ascq 59652, France. Electronic address: olivier.lafon@univ-lille1.fr.
4
Center of Interdisciplinary Magnetic Resonance, NHMFL, Tallahassee, FL 32310, USA.
5
Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China.
6
UCCS, CNRS, UMR 8181, University of Lille, Villeneuve d'Ascq 59652, France; Physics Department & Shanghai Key Laboratory of Magnetic Resonance, East China Normal University, Shanghai 200062, China. Electronic address: jean-paul.amoureux@univ-lille1.fr.

Abstract

Under Magic-Angle Spinning (MAS), a long radio-frequency (rf) pulse applied on resonance achieves the selective excitation of the center-band of a wide NMR spectrum. We show herein that these rf pulses can be applied on the indirect channel of Hetero-nuclear Multiple-Quantum Correlation (HMQC) sequences, which facilitate the indirect detection via spin-1/2 isotopes of nuclei exhibiting wide spectra. Numerical simulations show that this indirect excitation method is applicable to spin-1/2 nuclei experiencing a large chemical shift anisotropy, as well as to spin-1 isotopes subject to a large quadrupole interaction, such as (14)N. The performances of the long pulses are analyzed by the numerical simulations of scalar-mediated HMQC (J-HMQC) experiments indirectly detecting spin-1/2 or spin-1 nuclei, as well as by dipolar-mediated HMQC (D-HMQC) experiments achieving indirect detection of (14)N nuclei via (1)H in crystalline γ-glycine and N-acetyl-valine samples at a MAS frequency of 60kHz. We show on these solids that for the acquisition of D-HMQC spectra between (1)H and (14)N nuclei, the efficiency of selective moderate excitation with long-pulses at the (14)N Larmor frequency, ν0((14)N), is comparable to those with strong excitation pulses at ν0((14)N) or 2ν0((14)N) frequencies, given the rf field delivered by common solid-state NMR probes. Furthermore, the D-HMQC experiments also demonstrate that the use of long pulses does not produce significant spectral distortions along the (14)N dimension. In summary, the use of center-band selective weak pulses is advantageous for HMQC experiments achieving the indirect detection of wide spectra since it (i) requires a moderate rf field, (ii) can be easily optimized, (iii) displays a high robustness to CSAs, offsets, rf-field inhomogeneities, and fluctuations in MAS frequency, and (iv) is little dependent on the quadrupolar coupling constant.

KEYWORDS:

Indirect detection; Nitrogen-14; Overtone.; Selective excitation; Through-space HMQC; Very broad spectra

PMID:
26411981
DOI:
10.1016/j.ssnmr.2015.09.003
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center