Solution nuclear magnetic resonance spectroscopy on a nanostructured diamond chip

TL;DR

This paper presents a nanostructured diamond chip platform enabling highly sensitive NMR spectroscopy of picoliter-volume solutions at room temperature, with significant improvements in detection sensitivity over previous methods.

Contribution

The authors developed a nanostructured diamond chip with dense NV centers for enhanced NMR detection of tiny fluid volumes, achieving nearly two orders of magnitude better sensitivity.

Findings

Detected 19F spins in 1 pL volume with high SNR in 1 second.

Enhanced surface area by over 15 times using nanogratings.

Achieved room-temperature NMR detection at low magnetic fields.

Abstract

We demonstrate nuclear magnetic resonance (NMR) spectroscopy of picoliter-volume solutions with a nanostructured diamond chip. Using optical interferometric lithography, diamond surfaces were nanostructured with dense, high-aspect-ratio nanogratings, enhancing the surface area by more than a factor of 15 over mm^2 regions of the chip. The nanograting sidewalls were doped with nitrogen-vacancy (NV) centers so that more than 10 million NV centers in a (25 micrometer)^2 laser spot are located close enough to the diamond surface (5 nm) to detect the NMR spectrum of 1 pL of fluid lying within adjacent nanograting grooves. The platform was used to perform 1H and 19F NMR spectroscopy at room temperature in magnetic fields below 50 mT. Using a solution of CsF in glycerol, we demonstrate that 4 +/- 2 x 10^12 19F spins in a 1 pL volume, can be detected with a signal-to-noise ratio of 3 in 1 s integration. This represents nearly two orders of magnitude improvement in concentration sensitivity over previous NV and picoliter NMR studies.