Heating of samples induced by fast magic-angle spinning.

Area of Science:

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

Background:

• High-speed magic-angle spinning (MAS) is crucial for high-resolution solid-state NMR.
• Sample heating during MAS can introduce artifacts and affect spectral quality.
• Understanding and mitigating MAS-induced heating is essential for accurate NMR analysis.

Purpose of the Study:

• To investigate and quantify sample heating during high-speed MAS.
• To examine the influence of probehead design, spinner, and bearing air temperature on MAS heating.
• To assess the impact of MAS-induced heating on chemical shift parameters and spectral resolution.

Main Methods:

• Experimental demonstration of intense sample heating (up to 58 K temperature difference) via high-speed MAS.
• Systematic examination of probehead and spinner design effects.
• Analysis of bearing air temperature influence on sample temperature.

Main Results:

• Significant sample heating was observed during high-speed MAS.
• Probehead and spinner design, along with bearing air temperature, play a critical role in MAS-induced heating.
• Temperature gradients up to 12 K within the sample were detected.
• MAS-induced heating can affect the accurate determination of chemical shift values and tensor parameters.

Conclusions:

• High-speed MAS can lead to substantial sample heating, impacting NMR data accuracy.
• Careful consideration of experimental setup (probehead, spinner, air temperature) is necessary to minimize heating effects.
• MAS-induced heating and temperature gradients may limit spectral resolution in high-speed 1H MAS NMR.