Lee, Hyun Joon, Seong-Joo Lee, Jeong Hyun Shim, Han Seb Moon, and Kiwoong Kim. “In-Situ Overhauser-Enhanced Nuclear Magnetic Resonance at Less than 1 μ T Using an Atomic Magnetometer.” Journal of Magnetic Resonance 300 (March 2019): 149–52.
The development of atomic magnetometers has led to nuclear magnetic resonance (NMR) in zero and ultralow magnetic ﬁelds without using cryogenic sensors. However, in-situ detection, meaning that a sample locates in the detection space beside a vapor cell, has been conducted only with parahydrogen-induced polarization. Other hyperpolarization techniques remain unexplored yet. In this work, we demonstrate that Overhauser dynamic nuclear polarization allows in-situ NMR detection with an atomic magnetometer at less than 1 lT. The 1H NMR signal of a nitroxide radical solution was observed at 13.83 Hz, which corresponds to 325 nT. Signal-to-noise ratio was 32 after sixteen averages. On the Larmor precession of 1H spins, a decaying oscillation was superimposed. We attribute it to a transient 87Rb spin precession in response to a non-adiabatic ﬁeld variation. This work shows a new capability of zero- and ultralow-ﬁeld NMR.