@article {1450, title = {Long-lived Heteronuclear Spin-Singlet States in Liquids at a Zero Magnetic Field}, journal = {Physical Review Letters}, volume = {112}, year = {2014}, pages = {077601}, chapter = {077601}, author = {Emondts, M. and Ledbetter, M. P. and Pustelny, S. and Theis, T. and Patton, B. and Blanchard, J. W. and Butler, M. C. and Budker, D. and Pines, A.} } @article {1475, title = {Ultra-Low-Field NMR Relaxation and Diffusion Measurements Using an Optical Magnetometer (Cover Article)}, journal = {Angewandte Chemie}, volume = {53}, year = {2014}, month = {09/2014}, pages = {1-6}, doi = {DOI: 10.1002/anie.201403416}, author = {Ganssle, P. J. and Shin, H. D. and Seltzer, S. J. and Bajaj, V.S. and Ledbetter, M. P. and Budker, D. and Knappe, S. and Kitching, J. and Pines, A} } @article {247, title = {High-Resolution Zero-Field NMR J-Spectroscopy of Aromatic Compounds}, journal = {Journal of the American Chemical Society}, volume = {135}, year = {2013}, note = {J Am Chem Soc103RNTimes Cited:0Cited References Count:59}, month = {02/2013}, pages = {3607-3612}, abstract = {

We report the acquisition and interpretation of nuclear magnetic resonance (NMR) J-spectra at zero magnetic field for a series of benzene derivatives, demonstrating the analytical capabilities of zero-field NMR The zeroth-order spectral patterns do not overlap, which allows for straightforward determination of the spin interactions of substituent functional groups. Higher-order effects cause additional line splittings, revealing additional molecular information. We demonstrate resonance linewidths as narrow as 11 mHz, permitting resolution of minute frequency differences and precise determination of long-range J-couplings. The measurement of J-couplings with the high precision offered by zero-field NMR may allow further refinements in the determination of molecular structure and conformation.

}, keywords = {density}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja312239v}, url = {://WOS:000315936700050}, author = {Blanchard, J. W. and Ledbetter, M. P. and Theis, T. and Butler, M. C. and Budker, D. and Pines, A.} } @article {251, title = {Liquid-State Nuclear Spin Comagnetometers}, journal = {Physical Review Letters}, volume = {108}, year = {2012}, note = {Phys Rev Lett973FATimes Cited:0Cited References Count:36}, month = {Jun 15}, abstract = {

We discuss nuclear spin comagnetometers based on ultralow-field nuclear magnetic resonance in mixtures of miscible solvents, each rich in a different nuclear spin. In one version thereof, Larmor precession of protons and F-19 nuclei in a mixture of thermally polarized pentane and hexafluorobenzene is monitored via a sensitive alkali-vapor magnetometer. We realize transverse relaxation times in excess of 20 s and suppression of magnetic field fluctuations by a factor of 3400. We estimate it should be possible to achieve single-shot sensitivity of about 5 x 10(-9) Hz, or about 5 x 10(-11) Hz in approximate to 1 day of integration. In a second version, spin precession of protons and Xe-129 nuclei in a mixture of pentane and hyperpolarized liquid xenon is monitored using superconducting quantum interference devices. Application to spin-gravity experiments, electric dipole moment experiments, and sensitive gyroscopes is discussed.

}, keywords = {nmr}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.108.243001}, url = {://WOS:000306342000010}, author = {Ledbetter, M. P. and Pustelny, S. and Budker, D. and Romalis, M. V. and Blanchard, J. W. and Pines, A.} } @article {248, title = {Zero-Field NMR Enhanced by Parahydrogen in Reversible Exchange}, journal = {Journal of the American Chemical Society}, volume = {134}, year = {2012}, note = {J Am Chem Soc909GLTimes Cited:2Cited References Count:40}, month = {02/2012}, pages = {3987-3990}, 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 para-hydrogen-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 mu L, 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.

}, keywords = {gas}, isbn = {0002-7863}, doi = {Doi 10.1021/Ja2112405}, url = {://WOS:000301550800015}, author = {Theis, T. and Ledbetter, M. P. and Kervern, G. and Blanchard, J. W. and Ganssle, P. J. and Butler, M. C. and Shin, H. D. and Budker, D. and Pines, A.} } @article {258, title = {Near-Zero-Field Nuclear Magnetic Resonance}, journal = {Physical Review Letters}, volume = {107}, year = {2011}, note = {Phys Rev Lett813YOTimes Cited:5Cited References Count:26}, month = {Sep 1}, abstract = {

We investigate nuclear magnetic resonance (NMR) in near zero field, where the Zeeman interaction can be treated as a perturbation to the electron mediated scalar interaction (J coupling). This is in stark contrast to the high-field case, where heteronuclear J couplings are normally treated as a small perturbation. We show that the presence of very small magnetic fields results in splitting of the zero-field NMR lines, imparting considerable additional information to the pure zero-field spectra. Experimental results are in good agreement with first-order perturbation theory and with full numerical simulation when perturbation theory breaks down. We present simple rules for understanding the splitting patterns in near-zero-field NMR, which can be applied to molecules with nontrivial spectra.

}, keywords = {mri}, isbn = {0031-9007}, doi = {Doi 10.1103/Physrevlett.107.107601}, url = {://WOS:000294406600017}, author = {Ledbetter, M. P. and Theis, T. and Blanchard, J. W. and Ring, H. and Ganssle, P. and Appelt, S. and Blumich, B. and Pines, A. and Budker, D.} } @article {253, title = {Parahydrogen-enhanced zero-field nuclear magnetic resonance}, journal = {Nature Physics}, volume = {7}, year = {2011}, note = {Nat Phys786FYTimes Cited:9Cited References Count:31}, month = {Jul}, pages = {571-575}, abstract = {

Nuclear magnetic resonance, conventionally detected in magnetic fields of several tesla, is a powerful analytical tool for the determination of molecular identity, structure and function. With the advent of prepolarization methods and detection schemes using atomic magnetometers or superconducting quantum interference devices, interest in NMR in fields comparable to the Earth\&$\#$39;s magnetic field and below (down to zero field) has been revived. Despite the use of superconducting quantum interference devices or atomic magnetometers, low-field NMR typically suffers from low sensitivity compared with conventional high-field NMR. Here we demonstrate direct detection of zero-field NMR signals generated through parahydrogen-induced polarization, enabling high-resolution NMR without the use of any magnets. The sensitivity is sufficient to observe spectra exhibiting (13)C-(1)H scalar nuclear spin-spin couplings (known as J couplings) in compounds with (13)C in natural abundance, without the need for signal averaging. The resulting spectra show distinct features that aid chemical fingerprinting.

}, keywords = {order}, isbn = {1745-2473}, doi = {Doi 10.1038/Nphys1986}, url = {://WOS:000292290000017}, author = {Theis, T. and Ganssle, P. and Kervern, G. and Knappe, S. and Kitching, J. and Ledbetter, M. P. and Budker, D. and Pines, A.} } @article {268, title = {Optical detection of NMR J-spectra at zero magnetic field}, journal = {Journal of Magnetic Resonance}, volume = {199}, year = {2009}, note = {J Magn Reson456YJTimes Cited:19Cited References Count:26}, month = {Jul}, pages = {25-29}, abstract = {

Scalar couplings of the form JI(1) . 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 oil microchip devices for multiplexed Screening, assaying, and sample identification in chemistry and biomedicine. (C) 2009 Elsevier Inc. All rights reserved.

}, keywords = {cells}, isbn = {1090-7807}, doi = {Doi 10.1016/J.Jmr.2009.03.008}, url = {://WOS:000266890300004}, author = {Ledbetter, M. P. and Crawford, C. W. and Pines, A. and Wemmer, D. E. and Knappe, S. and Kitching, J. and Budker, D.} } @article {275, title = {Remote detection of nuclear magnetic resonance with an anisotropic magnetoresistive sensor}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {105}, year = {2008}, note = {P Natl Acad Sci USA266XBTimes Cited:8Cited References Count:17}, month = {Feb 19}, pages = {2271-2273}, abstract = {

We report the detection of nuclear magnetic resonance (NMR) using an anisotropic magnetoresistive (AMR) sensor. A \"remote-detection\" arrangement was used in which protons in flowing water were prepolarized in the field of a superconducting NMR magnet, adiabatically inverted, and subsequently detected with an AMR sensor situated downstream from the magnet and the adiabatic inverter. AMR sensing is well suited for NMR detection in microfluidic \"lab-on-a-chip\" applications because the sensors are small, typically on the order of 10 mu m. An estimate of the sensitivity for an optimized system indicates that approximate to 6 x 10(13) protons in a volume of 1,000 mu m(3), prepolarized in a 10-kG magnetic field, can be detected with a signal-to-noise ratio of 3 in a 1-Hz bandwidth. This level of sensitivity is competitive with that demonstrated by microcoils in superconducting magnets and with the projected sensitivity of microfabricated atomic magnetometers.

}, keywords = {mri}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.0712129105}, url = {://WOS:000253469900006}, author = {Verpillat, F. and Ledbetter, M. P. and Xu, S. and Michalak, D. J. and Hilty, C. and Bouchard, L. S. and Antonijevic, S. and Budker, D. and Pines, A.} } @article {279, title = {Zero-field remote detection of NMR with a microfabricated atomic magnetometer}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {105}, year = {2008}, note = {P Natl Acad Sci USA266XBTimes Cited:37Cited References Count:26}, month = {Feb 19}, pages = {2286-2290}, abstract = {

We demonstrate remote detection of nuclear magnetic resonance (NMR) with a microchip sensor consisting of a microfluidic channel and a microfabricated vapor cell (the heart of an atomic magnetometer). Detection occurs at zero magnetic field, which allows operation of the magnetometer in the spin-exchange relaxation-free (SERF) regime and increases the proximity of sensor and sample by eliminating the need for a solenoid to create a leading field. We achieve pulsed NMR linewidths of 26 Hz, limited, we believe, by the residence time and flow dispersion in the encoding region. In a fully optimized system, we estimate that for 1 s of integration, 7 x 10(13) protons in a volume of 1 mm(3), prepolarized in a 10-kG field, can be detected with a signal-to-noise ratio of approximate to 3. This level of sensitivity is competitive with that demonstrated by microcoils in 100-kG magnetic fields, without requiring superconducting magnets.

}, keywords = {mri}, isbn = {0027-8424}, doi = {Doi 10.1073/Pnas.0711505105}, url = {://WOS:000253469900009}, author = {Ledbetter, M. P. and Savukov, I. M. and Budker, D. and Shah, V. and Knappe, S. and Kitching, J. and Michalak, D. J. and Xu, S. and Pines, A.} }