71Ga-77Se connectivities and proximities in gallium selenide crystal and glass probed by solid-state NMR

• Published in: Journal of magnetic resonance (1997) Vol. 282; pp. 71 - 82
• Main Authors: Nagashima, Hiroki, Trébosc, Julien, Calvez, Laurent, Pourpoint, Frédérique, Mear, François, Lafon, Olivier, Amoureux, Jean-Paul
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01-09-2017
• Subjects: 71Ga; 77Se; D-HMQC; J-HMQC; J-RINEPT; Quadrupolar nuclei; STMAS-QCPMG; J-RINEPT; D-HMQC; J-HMQC; Quadrupolar nuclei; 77Se; STMAS-QCPMG; 71Ga
• ISSN: 1090-7807; 1096-0856
• DOI: 10.1016/j.jmr.2017.07.009

0.2Ga2Se3-0.8GeSe2 glass 2D HETCOR spectra at B0=9.4T.
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•77Se-71Ga HETCOR experiments.•71Ga STMAS-QCPMG.•Measurement of 77Se-71GaJ-couplings.•Comparison of J-HMQC, D-HMQC and J-RINEPT techniques.•Structural analysis of chalcogenide glasses.
We introduce two-dimensional (2D) 71Ga-77Se through-bond and through-space correlation experiments. Such correlations are achieved using (i) the J-mediated Refocused Insensitive Nuclei Enhanced by Polarization Transfer (J-RINEPT) method with 71Ga excitation and 77Se Carr-Purcell-Meiboon-Gill (CPMG) detection, as well as (ii) the J- or dipolar-mediated Hetero-nuclear Multiple-Quantum Correlation (J- or D-HMQC) schemes with 71Ga excitation and quadrupolar CPMG (QCPMG) detection. These methods are applied to the crystalline β-Ga2Se3 and the 0.2Ga2Se3-0.8GeSe2 glass. Such glass leads to a homogeneous and reproducible glass–ceramic, which is a good alternative to single-crystalline Ge and polycrystalline ZnSe materials for making lenses transparent in the IR range for thermal imaging applications. We show that 2D 71Ga-77Se correlation experiments allow resolving the 77Se signals of molecular units, which are not resolved in the 1D 77Se CPMG spectrum. Additionally, the build-up curves of the J-RINEPT and the J-HMQC experiments allow the estimate of the 71Ga-77Se J-couplings via one and three-bonds in the three-dimensional network of β-Ga2Se3. Furthermore, these build-up curves show that the one-bond 1J71Ga-77Se couplings in the 0.2Ga2Se3-0.8GeSe2 glass are similar to those measured for β-Ga2Se3. We also report 2D 71Ga Satellite Transition Magic-Angle Spinning (STMAS) spectrum of β-Ga2Se3 using QCPMG detection at high magnetic field and high Magic-Angle Spinning frequency using large radio frequency field. Such spectrum allows separating the signal of β-Ga2Se3 and that of an impurity.