title: Optical detection of NMR J-spectra at zero magnetic field.
abstract: Scalar couplings of the form JI(1) x I(2) between nuclei impart valuable information about molecular structure to nuclear magnetic-resonance spectra. Here we demonstrate direct detection of J-spectra due to both heteronuclear and homonuclear J-coupling in a zero-field environment where the Zeeman interaction is completely absent. We show that characteristic functional groups exhibit distinct spectra with straightforward interpretation for chemical identification. Detection is performed with a microfabricated optical atomic magnetometer, providing high sensitivity to samples of microliter volumes. We obtain 0.1 Hz linewidths and measure scalar-coupling parameters with 4-mHz statistical uncertainty. We anticipate that the technique described here will provide a new modality for high-precision "J spectroscopy" using small samples on microchip devices for multiplexed screening, assaying, and sample identification in chemistry and biomedicine.
authors.affiliation: Department of Physics, University of California, Berkeley, CA 94720-7300, USA. ledbetter@berkeley.edu
authors.forename: M P
authors.initials: MP
authors.lastname: Ledbetter
authors.forename: C W
authors.initials: CW
authors.lastname: Crawford
authors.forename: A
authors.initials: A
authors.lastname: Pines
authors.forename: D E
authors.initials: DE
authors.lastname: Wemmer
authors.forename: S
authors.initials: S
authors.lastname: Knappe
authors.forename: J
authors.initials: J
authors.lastname: Kitching
authors.forename: D
authors.initials: D
authors.lastname: Budker
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation*; D008280:Magnetics / Q000295:instrumentation*; D055096:Optical Devices; D012031:Refractometry / Q000295:instrumentation*; D013057:Spectrum Analysis / Q000295:instrumentation*