Microwave-free nuclear magnetic resonance at molecular scales

James D A Wood,Alastair Stacey,Jean-Philippe Tetienne,Liam T Hall,David A Broadway,David A Simpson,Lloyd C L Hollenberg

doi:10.1038/ncomms15950

Abstract

The implementation of nuclear magnetic resonance (NMR) at the nanoscale is a major challenge, as the resolution of conventional methods is limited to mesoscopic scales. Approaches based on quantum spin probes, such as the nitrogen-vacancy (NV) centre in diamond, have achieved nano-NMR under ambient conditions. However, the measurement protocols require application of complex microwave pulse sequences of high precision and relatively high power, placing limitations on the design and scalability of these techniques. Here we demonstrate NMR on a nanoscale organic environment of proton spins using the NV centre while eliminating the need for microwave manipulation of either the NV or the environmental spin states. We also show that the sensitivity of our significantly simplified approach matches that of existing techniques using the NV centre. Removing the requirement for coherent manipulation while maintaining measurement sensitivity represents a significant step towards the development of robust, non-invasive nanoscale NMR probes.

Highlights

The implementation of nuclear magnetic resonance (NMR) at the nanoscale is a major challenge, as the resolution of conventional methods is limited to mesoscopic scales
The microwave-free technique for magnetic resonance spectroscopy is based on T1 relaxometry detection[7,27,28,29,30] and precise magnetic field tuning to bring the NV into resonance with the Zeeman split target spin transitions[31,32,33,34]
This technique was proposed and demonstrated for quantitative electron spin resonance spectroscopy using an ensemble of NV centres[25] and extended to hyperfine-coupled nuclear spin spectroscopy with single NV centres[35]

Summary

Introduction

The implementation of nuclear magnetic resonance (NMR) at the nanoscale is a major challenge, as the resolution of conventional methods is limited to mesoscopic scales. We demonstrate microwave-free nano-NMR on a nanoscopic sample of proton nuclear spins within an organic sample external to the diamond.

Results

Conclusion