471788 Towards the Next Generation of Magnetic Resonance Spectroscopy: Harnessing Light and Spin

Sunday, November 13, 2016
Continental 4 & 5 (Hilton San Francisco Union Square)
Jonathan King, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA; Department of Chemistry, University of California, Berkeley, Berkeley, CA

Research Interests:

With unmatched chemical specificity and the ability to probe materials across length- and timescales, nuclear magnetic resonance spectroscopy (NMR) and imaging (MRI) are two of the most powerful analytical techniques available to engineers, scientists, and medical professionals. However, they require costly infrastructure and are plagued by low sensitivity resulting from small nuclear spin magnetization. Typically, nuclear spin magnetization is generated by allowing the sample to equilibrate in a magnetic field. However, even with the largest available superconducting magnets, room-temperature equilibrium magnetization is only about 10-5 of the theoretical maximum. A general method to generate non-equilibrium nuclear spin magnetization would allow us to dispense with superconducting magnets, decrease sensitivity limits and experimental time by orders of magnitude, and enable a range of previously inaccessible applications.

With this motivation, my laboratory will be organized around three main thrusts:

  1. Enhancement of sensitivity for NMR.
  2. Exploration of new magnetic resonance applications at low- and zero-fields.
  3. Fundamental aspects of spectroscopy, chirality, and condensed-matter physics.

Our primary goal is to harness the pure spin states of photons and electrons to achieve nuclear spin polarization. We will build upon my previous work with optical pumping in semiconductors [1] and nitrogen vacancy (NV-) centers in diamond [2], where I have demonstrated a 170,000-fold increase in NMR signal from the 13C nuclei in the diamond by coupling the electron and nuclear spin states with microwave irradiation. Future work involves the transfer of this nuclear magnetization to arbitrary samples of interest. This will require development of high-surface area diamond structures, fundamental studies of spin polarization transfer mechanisms, and modification of the diamond surface chemistry.

We also seek to extend NMR beyond the traditional model requiring a high-field superconducting magnet in a dedicated facility. Low-field NMR allows the use of cheap, portable magnets in benchtop and truly portable systems. Zero-field NMR allows the observation of spin-interactions that are invisible in the presence of a magnetic field, providing additional information about material structure, geometry, and dynamics [3]. Furthermore, zero-field experiments are free from the deleterious effects of inhomogeneous magnetic susceptibility, enabling high-resolution study of heterogeneous materials.

My laboratory will study fundamental aspects of spectroscopy including chiral effects of spin-spin couplings and spin dynamics in condensed matter. We anticipate ability to ability to directly resolve molecular chirality through antisymmetric spin-spin interactions without the addition of chiral derivatizing agents. Experimental and theoretical studies of spin dynamics in many-body solid-state systems are important to the understanding of solid-state NMR spectroscopy and also provide a prototypical test bed for concepts in condensed-matter physics.

  1. King, J. P. et al. “Optically rewritable patterns of nuclear magnetization in gallium arsenide.” Nature Communications 3:918 doi: 10.1038/ncomms1918 (2012).
  2. King, J. P. et al. “Room-temperature in situ nuclear spin hyperpolarization from optically pumped nitrogen vacancy centres in diamond.” Nature Communications 6:8965 doi: 10.1038/ncomms9965 (2015).
  3. J. W. Blanchard, T. F. Sjolander, J. P. King, M. P. Ledbetter, E. H. Levine, V. S. Bajaj, D. Budker, and A. Pines. “Measurement of untruncated nuclear spin interactions via zero- to ultralow-field nuclear magnetic resonance.” Phys. Rev. B 92, 220202(R) (2015).

Teaching Interests:

My teaching philosophy can be stated concisely: effective teaching is the facilitation of effective learning. While this statement is simple, in practice it presents these challenges: How do we define effective learning? How do we assess if learning has occurred? What steps do we take based on this assessment? I will present my plan to address these challenges in the chemical engineering curriculum. I am interested in teaching all aspects of the core curriculum, but with my background would be especially interested in teaching thermodynamics, fluid dynamics, and transport phenomena at the undergraduate and graduate levels. I would also develop special classes in the theory and application of spectroscopic techniques.

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