John W. Blanchard
University of California, Berkeley
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Featured researches published by John W. Blanchard.
Journal of the American Chemical Society | 2012
Thomas Theis; Micah P. Ledbetter; Gwendal Kervern; John W. Blanchard; Paul J. Ganssle; Mark C. Butler; Hyun Doo Shin; Dmitry Budker; Alexander Pines
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.
Journal of the American Chemical Society | 2013
John W. Blanchard; Micah P. Ledbetter; Thomas Theis; Mark C. Butler; Dmitry Budker; Alexander Pines
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.
Physical Review B | 2015
John W. Blanchard; Tobias F. Sjolander; Jonathan P. King; Micah P. Ledbetter; Emma H. Levine; Vikram S. Bajaj; Dmitry Budker; Alexander Pines
Author(s): Blanchard, JW; Sjolander, TF; King, JP; Ledbetter, MP; Levine, EH; Bajaj, VS; Budker, D; Pines, A | Abstract:
Applied Physics Letters | 2016
Arne Wickenbrock; N. Leefer; John W. Blanchard; Dmitry Budker
We use a radio-frequency
Journal of Chemical Physics | 2013
Mark C. Butler; Micah P. Ledbetter; Thomas Theis; John W. Blanchard; Dmitry Budker; Alexander Pines
^{85}
Physical Review Letters | 2012
Micah P. Ledbetter; Szymon Pustelny; Dmitry Budker; Michael Romalis; John W. Blanchard; Alexander Pines
Rb alkali-vapor cell magnetometer based on a paraffin-coated cell with long spin-coherence time and a small, low-inductance driving coil to create highly resolved conductivity maps of different objects. We resolve sub-mm features in conductive objects, we characterize the frequency response of our technique, and by operating at frequencies up to 250 kHz we are able to discriminate between differently conductive materials based on the induced response. The method is suited to cover a wide range of driving frequencies and can potentially be used for detecting non-metallic objects with low DC conductivity.
arXiv: Instrumentation and Detectors | 2018
Antoine Garcon; Deniz Aybas; John W. Blanchard; Gary Centers; Nataniel L. Figueroa; Peter W. Graham; Derek F. Jackson Kimball; Surjeet Rajendran; Marina Gil Sendra; Alexander Sushkov; Lutz Trahms; Tao Wang; Arne Wickenbrock; Teng Wu; Dmitry Budker
For liquid samples at Earths field or below, nuclear-spin motion within scalar-coupled networks yields multiplets as a spectroscopic signature. In weak fields, the structure of the multiplets depends on the magnitude of the Zeeman interaction relative to the scalar couplings; in Earths field, for example, heteronuclear couplings are truncated by fast precession at distinct Larmor frequencies. At zero field, weak scalar couplings are truncated by the relatively fast evolution associated with strong scalar couplings, and the truncated interactions can be described geometrically. When the spin system contains a strongly coupled subsystem A, an average over the fast evolution occurring within the subsystem projects each strongly coupled spin onto FA, the summed angular momentum of the spins in A. Weakly coupled spins effectively interact with FA, and the coupling constants for the truncated interactions are found by evaluating projections. We provide a formal description of zero-field spin systems with truncated scalar couplings while also emphasizing visualization based on a geometric model. The theoretical results are in good agreement with experimental spectra that exhibit second-order shifts and splittings.
Journal of Chemical Physics | 2013
Mark C. Butler; Gwendal Kervern; Thomas Theis; Micah P. Ledbetter; Paul J. Ganssle; John W. Blanchard; Dmitry Budker; Alexander Pines
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 19F 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 5×10(-9) Hz, or about 5×10(-11) Hz in ≈1 day of integration. In a second version, spin precession of protons and 129Xe 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.
Journal of Physical Chemistry Letters | 2017
Jonathan P. King; Tobias F. Sjolander; John W. Blanchard
The Cosmic Axion Spin Precession Experiment (CASPEr) is a nuclear magnetic resonance experiment (NMR) seeking to detect axion and axion-like particles which could make up the dark matter present in the universe. We review the predicted couplings of axions and axion-like particles with baryonic matter that enable their detection via NMR. We then describe two measurement schemes being implemented in CASPEr. The first method, presented in the original CASPEr proposal, consists of a resonant search via continuous-wave NMR spectroscopy. This method offers the highest sensitivity for frequencies ranging from a few Hz to hundreds of MHz, corresponding to masses
Review of Scientific Instruments | 2017
Michael C. D. Tayler; Thomas Theis; Tobias F. Sjolander; John W. Blanchard; Arne Kentner; Szymon Pustelny; Alexander Pines; Dmitry Budker
m_{\rm a} \sim 10^{-14}