Determination of Al-Si connectivities in zeolites with 2D Al-Si RAPT-CPMG-HETCOR NMR
The recently introduced concept of the combined use of rotor assisted population transfer (RAPT) and Carr-Purcell-Meiboom-Gill (CPMG) techniques to boost the sensitivity of cross polarization (CP) based NMR experiments is applied to a synthetic zeolite (ZSM-4). The sensitivity was increased by a factor of 4, which enabled acquisition of a high quality two-dimensional {sup 27}Al-{sup 29}Si HETCOR (heteronuclear correlation) spectrum. By separating the resonances in two dimensions, through-space connectivities between spins were revealed and the effective resolution was improved in both dimensions, which allowed determination of the existing ambiguities in spectral assignments in this material. The spectra provided clear indication of random distribution of aluminum and silicon within the ZSM-4 network. Additionally, unexpected correlations were observed between different components of inhomogeneously broadened {sup 29}Si and {sup 27}Al lines, which are most likely due to differences in the second coordination sphere environments.
- Research Organization:
- Ames Laboratory (AMES), Ames, IA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- AC02-07CH11358
- OSTI ID:
- 962645
- Report Number(s):
- IS-J 7352
- Journal Information:
- Solid State Nuclear Magnetic Resonance, Journal Name: Solid State Nuclear Magnetic Resonance Journal Issue: 4 Vol. 33; ISSN 0926-2040
- Country of Publication:
- United States
- Language:
- English
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