To understand how a material works, one must observe its surface at the atomic scale. Scientists have developed a variant of hyperpolarized surface NMR that avoids any contact between the amplifying agent and the material being studied. Tested on a highly reactive catalyst, this technique paves the way for the analysis of surfaces that were previously inaccessible.

The properties of a functional material are often linked to those of its surface. In a catalyst, for example, this is where the active sites are located. Depending on their arrangement and chemical nature, the catalyst may or may not be effective, but to understand why, it is necessary to observe this surface atom by atom. To do this, scientists rely in particular on solid-state nuclear magnetic resonance (NMR), which provides information about the chemical environment of atomic nuclei.

For the past fifteen years, dynamic nuclear polarization (DNP) has made it possible to amplify the signal from nuclei present on the surface. How does it work? By adding molecules containing unpaired electrons to the solid being studied. These molecules transfer their polarization to the atomic nuclei, thereby strengthening their signal. The problem is that, on highly reactive materials, the added molecules can degrade upon contact with the surface or even alter it. The measurement then risks modifying the very property it seeks to characterize.

Learn more on the CNRS website

Reference

“Surface-Enhanced NMR Spectroscopy via Solid-to-Solid Relayed Dynamic Nuclear Polarization”, Salah-Eddine Akrial, Nghia Huu Le, Soleyah Houguet, Teresa Insinna, Hugo Lingua, Domenico Gioffrè, Gilles Casano, Charline Dalverny, Andrey V. Pichugov, Laurent Veyre, Judith Schlagnitweit, Christophe Copéret, David Gajan, Clément Camp, Olivier Ouari, Chloé Thieuleux, Anne Lesage. Journal of the American Chemical Society, 2026.
DOI: https://doi.org/10.1021/jacs.6c09647