Sealing effect of magic-angle-spinning rotors in solid-state NMR

Area of Science:

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

Background:

• Magic-angle-spinning (MAS) rotors are crucial for high-resolution solid-state NMR.
• Ensuring rotor seal integrity is vital to prevent sample contamination and experimental errors.
• Current methods for assessing rotor sealing may lack quantitative accuracy.

Purpose of the Study:

• To develop and validate quantitative methods for checking the sealing performance of MAS rotors.
• To differentiate between moisture intrusion and gas leakage within MAS rotors.
• To provide reliable techniques for quality control of MAS rotor sealing.

Main Methods:

• Utilizing trimethylphosphine oxide, a hygroscopic compound, to detect moisture intrusion via (31)P MAS NMR.
• Employing (1)H MAS NMR to independently monitor hydrated, crystalline, and adsorbed water forms.
• Assessing gas leakage using (129)Xe MAS NMR of xenon in zeolites and (3)He MAS NMR of helium-3 gas.

Main Results:

• Trimethylphosphine oxide effectively distinguishes between anhydrous and hydrated forms in (31)P MAS NMR spectra.
• (1)H MAS NMR provides independent monitoring of different water species.
• (129)Xe and (3)He MAS NMR spectra allow for quantitative assessment of gas leakage.

Conclusions:

• The proposed methods offer a quantitative and reliable approach to assess MAS rotor sealing.
• These techniques can be implemented to ensure the integrity of MAS rotors for various applications.
• The study provides a framework for routine quality control of MAS rotor sealing performance.