High-sensitivity multichannel zero-to-ultralow field NMR with atomic magnetometer arrays

Abstract

Despite its versatility and high chemical specificity, conventional NMR spectroscopy is limited in measurement throughput due to the need for high-homogeneity magnetic fields, necessitating sequential sample analysis, and bulky devices. Here, we propose a multichannel NMR device that overcomes these limitations that leverages the zero-to-ultralow field (ZULF) regime, where simultaneous detection of multiple samples is carried out via an array of compact optically pumped magnetometers (OPMs). A magnetic field is used only for pre-polarization, permitting the use of large-bore, high-field, inhomogeneous magnets that can accommodate many samples concurrently. Through systematic advances, we demonstrate high-sensitivity, high resolution ZULF NMR spectroscopy with sensitivity comparable to benchtop NMR systems. The spectroscopy remains robust without the need for field shimming for periods on the order of weeks. We show the detection of ZULF NMR signals from organic molecules without isotopic enrichment, and demonstrate the parallelized detection of three distinct samples simultaneously as a proof-of-concept, with the potential to scale further to over 100 channels at a cost comparable to high-resolution liquid state NMR systems. This work sets the stage for using multichannel "NMR camera" devices for inline reaction monitoring, robotic chemistry, quality control, and high-throughput assays.