nanoNMR

nanoNMR refers to a set of techniques for performing nuclear magnetic resonance spectroscopy at nanometer to micrometer length scales, using quantum sensors to detect the magnetic fields produced by nuclear spins in extremely small samples. The most widely used platform employs nitrogen-vacancy centers in diamond, where a single electron spin acts as a nanoscale magnetometer. Nuclear spins in nearby molecules create time-varying magnetic fields that perturb the NV spin, which is initialized and read out optically. By applying microwave pulse sequences that control spin dynamics, researchers extract information about the local nuclear spin environment, yielding NMR spectra or imaging contrast from very small volumes.

The approach operates under ambient conditions and supports a range of nuclei, including hydrogen, carbon, fluorine, and phosphorus. Information is gathered from the magnetic noise and coherent spin interactions detected by the NV center, enabling spectroscopy and, in some implementations, spatial localization of the sample by scanning the sensor or docking the sample near a shallow NV layer. Advances in coherence times and pulse sequences improve spectral resolution and sensitivity, enabling increasingly detailed nanoscale measurements.

Current achievements include detecting NMR signals from nanoscale samples containing thousands to millions of spins and performing basic spectroscopic measurements in confined volumes. While single-molecule NMR at the nanoscale remains a goal, nanoNMR has demonstrated the potential to provide structural and chemical information about tiny volumes that are inaccessible to conventional NMR.

Applications span structural biology, materials science, catalysis, and surface chemistry, with ongoing effort to enhance sensitivity, resolution, and integration with microfluidics and other analytical platforms.