title: Zero-field NMR enhanced by parahydrogen in reversible exchange.
abstract: We have recently demonstrated that sensitive and chemically specific NMR spectra can be recorded in the absence of a magnetic field using hydrogenative parahydrogen induced polarization (PHIP) (1-3)  and detection with an optical atomic magnetometer. Here, we show that non-hydrogenative parahydrogen-induced polarization (4-6)  (NH-PHIP) can also dramatically enhance the sensitivity of zero-field NMR. We demonstrate the detection of pyridine, at concentrations as low as 6 mM in a sample volume of 250 μL, with sufficient sensitivity to resolve all identifying spectral features, as supported by numerical simulations. Because the NH-PHIP mechanism is nonreactive, operates in situ, and eliminates the need for a prepolarizing magnet, its combination with optical atomic magnetometry will greatly broaden the analytical capabilities of zero-field and low-field NMR.
authors.affiliation: Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley California 94720, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Theis
authors.forename: Micah P
authors.initials: MP
authors.lastname: Ledbetter
authors.forename: Gwendal
authors.initials: G
authors.lastname: Kervern
authors.forename: John W
authors.initials: JW
authors.lastname: Blanchard
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Ganssle
authors.forename: Mark C
authors.initials: MC
authors.lastname: Butler
authors.forename: Hyun D
authors.initials: HD
authors.lastname: Shin
authors.forename: Dmitry
authors.initials: D
authors.lastname: Budker
authors.forename: Alexander
authors.initials: A
authors.lastname: Pines
mesh_terms: D006859:Hydrogen / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D011725:Pyridines / Q000032:analysis
chemical_list: D011725:Pyridines; D006859:Hydrogen; C023666:pyridine