This application note describes the applications and experimental considerations for FastMAS and UltraFastMAS techniques. FastMAS and UltraFastMAS techniques enable experiments with rotation speeds of 40 to 65 kHz, which reduces linewidths and suppresses spin diffusion caused by proton-proton dipolar interactions. These techniques enable experiments such as direct proton observe or solid-state HETCOR to collect spectra comparable to those that formerly required both spinning and experimentally difficult multiple-pulse homonuclear decoupling sequences. Another advantage of FastMAS and UltraFastMAS techniques is that they suppress spin diffusion between protons, allowing experiments to be conveniently performed on individual protons in single or multiple dimensional experiments.
This document provides an application note on the FastMAS and UltraFastMAS spinning systems developed by Agilent Technologies. It explains how high-speed magic angle spinning (MAS) up to 65 kHz averages dipolar interactions to achieve high-resolution NMR spectra in solids, comparable to liquid-state spectra. The text details the benefits of these systems for organic samples, including linewidth reduction and the suppression of spin diffusion.
| NMR Frequency used | 600 MHz |
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The primary benefit is linewidth reduction and suppression of spin diffusion brought about by averaging the proton-proton dipolar interaction.
The heating of a rotating cylinder is proportional to the square of the rotation rate.
The magnitude of heating can exceed 50 °C when running near maximum speed in the absence of external air flow.