RT Journal Article SR Electronic T1 Two-dimensional nuclear magnetic resonance spectroscopy with a microfluidic diamond quantum sensor JF Science Advances JO Sci Adv FD American Association for the Advancement of Science SP eaaw7895 DO 10.1126/sciadv.aaw7895 VO 5 IS 7 A1 Smits, Janis A1 Damron, Joshua T. A1 Kehayias, Pauli A1 McDowell, Andrew F. A1 Mosavian, Nazanin A1 Fescenko, Ilja A1 Ristoff, Nathaniel A1 Laraoui, Abdelghani A1 Jarmola, Andrey A1 Acosta, Victor M. YR 2019 UL http://advances.sciencemag.org/content/5/7/eaaw7895.abstract AB Quantum sensors based on nitrogen-vacancy centers in diamond have emerged as a promising detection modality for nuclear magnetic resonance (NMR) spectroscopy owing to their micrometer-scale detection volume and noninductive-based detection. A remaining challenge is to realize sufficiently high spectral resolution and concentration sensitivity for multidimensional NMR analysis of picoliter sample volumes. Here, we address this challenge by spatially separating the polarization and detection phases of the experiment in a microfluidic platform. We realize a spectral resolution of 0.65 ± 0.05 Hz, an order-of-magnitude improvement over previous diamond NMR studies. We use the platform to perform two-dimensional correlation spectroscopy of liquid analytes within an effective ∼40-picoliter detection volume. The use of diamond quantum sensors as in-line microfluidic NMR detectors is a major step toward applications in mass-limited chemical analysis and single-cell biology.