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.

No abstract

No abstract

No abstract

The dift'usion of hydrogen through the hexagonal metal hydride ZrBe&H& 4 has been studied by measuring the H nuclear spin-lattice relaxation rate T~a s a function of frequency and temperature. At high temperatures, where the hopping rate of the H interstitials is faster than the nuclear magnetic resonance (NMR) frequency, the relaxation rate has a frequency dependence much larger than expected for random diffusive motion in three dimensions. A previous NMR study of ZrBe2H& 4 did not account for the anomalous frequency dependence. Our data more fully define the frequency dependence, and we find that it is consistent with a model in which the motion of the hydrogen is restricted to two dimensions. Two-dimensional motion allows a self-consistent analysis of the Td ata for all the measured frequencies and provides an improved measure of the activation energy, E = 0.27 + 0.02 eV. The frequency dependence of T~c an be used to identify two-dimensional motion in a randomly oriented powder sample.