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High Field

Magic Angle Coil Spinning (MACS) Spectroscopy

    rotating microcoils MACS insertsNMR Spectroscopy of very small samples is very difficult using commercial equipment. The situation is even more hard when the sample is anisotropic and spectral resolution comes from sample spinning at the so-called magic angle. A microcoil can be wound around the sample and once tuned at the Larmor frequency, it can establish a wireless connection with the rest of a commercial probe electronics. It can be thus integrated inside the sample holder and spun with it at the magic angle. The solution is scaling favorably with size as long as the quality factor of the microcoil is non-negligable. The photo on the right shows two tuned MACS coils. Their typical dimensions vary from 1 millimeters down to 300 micrometers in outer diameter. We hope that modern lithographic techniques can reduce further their size.

    This technology is patented and avalailable for licening through the technology transfer of CEA. For more information please check the official website here.

    We are currently applying this approach to study nanomaterials, such as thin films used for the coating of surfaces. This project, named "nanoMACS" is supported by the C'Nano IdF Center of Competence.

Ultra Slow Magic Angle Turning Spectroscopy

    Magic Angle Turning Sign There are many cases where the spinning of the sample cannot be performed under ultra fast conditions, typically tens of kHz (tens of thousands of turns per second !). For example when the sample is temperature sensitive and/or hazardous. One class of pulse sequences can offer isotropic resolution even under ultra slow sample spinning conditions. These so-called magic angle turning approaches have been applied in our group for the study of inorganic glasses which are currently used for nuclear waste storage. Together with the isotropic chemical shift information, correlations with anisotropic interactions are obtained and can teach us more about the "structure" of amorphous materials. Such materials can also be paramagnetic and therefore needing extremely high spinning frequencies and low magnetic fields in order to aleviate susceptibility broadenings. Last but not least, these techniques have been recently applied to extract metabolic signatures in biopsy samples spinning at hundreds of Hz.


Magic Angle Spinning STRAFI Imaging

    Stray Field ImagingThe magnetic field away from the center of an NMR or MRI magnet can be extremely inhomogeneous (gradients up to 50 T/m or even higher). This gradient can encode the three space dimensions when the sample is spinning at the magic angle. This means that we do not need pulsed field gradients to obtain spatial encoding and 3D imaging. We are using this approach to acquire 3D images of microscopic samples. Spinning at the magic angle also aleviates anisotropic broadenings such as susceptibilty and/or dipolar couplings and renders the images more sensitive and having a better spatial resolution and definition.