Simultaneous MQMAS NMR Experiments for Two Half-Integer Quadrupolar Nuclei.

Area of Science:

• Solid-state Nuclear Magnetic Resonance (NMR) Spectroscopy
• Materials Chemistry
• Materials Science

Background:

• Efficient data acquisition is crucial for advanced NMR techniques like Multiple-Quantum Magic Angle Spinning (MQMAS).
• Traditional MQMAS experiments can be time-consuming, limiting throughput and accessibility.
• Optimizing instrument time is essential for routine analysis of complex materials.

Purpose of the Study:

• To develop and present a novel procedure for acquiring two MQMAS NMR experiments concurrently.
• To enhance the efficiency of instrument time utilization in solid-state NMR.
• To demonstrate the applicability of the method for specific nuclei (¹⁷O and ²⁷Al) in glass gel samples.

Main Methods:

• Utilized a triply tuned probe with multiple receivers for staggered data acquisition.
• Implemented a method where data for one nucleus is collected during the recovery delay of another, and vice versa.
• Applied the technique to record triple-quantum (3Q) ¹⁷O and 3Q or quintuple-quantum (5Q) ²⁷Al MAS NMR spectra.

Main Results:

• Achieved a reduction in instrument time to 60-80% of that required for single acquisition methods.
• Successfully acquired 3Q ¹⁷O and 3Q/5Q ²⁷Al MAS NMR spectra of a 1.18Na₂O•5SiO₂•Al₂O₃ glass gel.
• Demonstrated the feasibility of simultaneous acquisition for different quantum orders.

Conclusions:

• The presented procedure offers a significant improvement in NMR experiment efficiency.
• This method allows for more effective use of instrument time in solid-state NMR spectroscopy.
• The technique is particularly beneficial for analyzing materials like silicate-aluminate glasses.