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This is an exciting time in the history of vehicular transportation. The recent commercial introduction of hybrid electric vehicles coupled with the huge international effort to develop batteries and fuel cells for automotive use has made the dream of widespread electric vehicle use a real possibility. The last decade has seen the introduction of a variety of promising new materials for lithium rechargeable batteries, as well as a Federal initiative for the technological development of fuel cells. Reimer's research group, in collaboration with Professors Elton Cairns and Lutgard DeJonghe, has applied nuclear magnetic resonance (NMR) spectroscopy to the study of a variety of electrochemical systems, including proton-exchange membrane and solid oxide-fuel cells, as well as Li-ion batteries. For example, Reimer's group was the first to obtain carbon-13 NMR data from commercial fuel cell electrocatalysts, and then used electroanalytical methods, combined with NMR, to elucidate how NMR chemical shifts speciate active surfaces on platinum catalysts. His group also elucidated the role the electron-nuclear hyperfine interaction plays in determining the NMR "chemical" shifts of Li in the complex oxides that comprise electrode materials for batteries. His group is exploring, in collaboration with Prof. Lutgard DeJonghe, so-called "Norby's Gap" proton conductors for intermediate temperature hydrogen/biofuel fuel cells. These studies involve multi-dimensional solid-state NMR, as well as pulse-field gradient and stray-field diffusion measurements. People Aurora Marie Fojas, Joel Stettler, Dr. Jian Feng, Hassan Khan, Stephanie Didas. Representative Papers PEM Fuel Cells Proton Conductors Lithium Batteries |
 
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The Reimer group is engaged in a collaboration with LLNL researchers in a three-pronged approach for the design and development of NMR methods that yield scientific and engineering models for aging in elastomeric polymer non-polymer composites. The first approach has focused on the indirect determination and spatial resolution of shear modulus in a specific, poly(dimethylsiloxane)-based elastomer via nuclear magnetic resonance relaxation and imaging techniques. In our second approach, we seek to underpin the relationship between NMR properties and polymer mechanical properties through development of analytical theory that connects polymer physics to NMR observables. The third approach is aimed at using NMR as a molecular spectroscopic probe of the interface between filler surface and polymer chains, with particular attention to changes in the structure of these interfaces with thermal, mechanical, or radiological aging. The NMR-derived molecular details of this interface inform molecular dynamics simulations, with the ultimate goal of connecting these molecular views with macroscopic models for aging and device failure. People Brian Mayer Representative Papers Imaging Mechanical Properties |
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A particularly limiting feature of NMR spectroscopy and magnetic resonance imaging (MRI) is the miniscule magnitude of the expectation value for nuclear spin orientation: the Zeeman splittings between the nuclear spin energy levels are small relative to kT. Thus the vast majority of NMR and MRI methods are restricted to bulk systems. For this reason, considerable attention in the NMR/MRI community is focused on the development of methods for enhanced nuclear polarization. One strategy for overcoming the sensitivity limitations exploits the near-perfectly polarized electrons that can be generated in a number of ways, then uses the electron spin polarizations to effectively deliver high polarization to nuclei. Funded by an NSF NIRT, Professor Reimer, in collaboration with Professor Segalman and Prfs. Meriles and Tamargo at CCNY, are exploiting this strategy and have employed the optical excitation of organic and inorganic semiconductors and semiconductor-based nanostructures to provide electron spins that yield exotic NMR-observable nuclear spin populations. Our most recent results demonstrate voltage-tunable nuclear polarization without the need for ferromagnets or sample temperatures near tens of mK. People Jonathan King, Cody Merritt, Stephen Greenwald Representative Papers Nuclear Thermodynamics Nuclear Spintronics |
 
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In 2000 Prof Reimer began a collaboration with Professor Douglas Clark and Professor Jonathan Dordick (RPI) to use spectroscopic methods to study nonaqueous biocatalysis, i.e., applications of enzymes in organic media or nearly anhydrous environments. Nonaqueous biocatalysis, including enzymatic reactions in nearly anhydrous organic solvents, has emerged as a practical tool for chemical synthesis that exploits the exquisite chemo-, regio-, and enantio-selectivities demonstrated commonly by enzymes, yet avoids the limitations of aqueous enzymatic catalysis. Unfortunately, little is understood about the mechanistic details of non-aqueous biocatalysis. Reimer's role in the collaboration is to provide a host of liquid- and solid-state NMR techniques that are aimed at elucidating the mechanism whereby enzymes are activated for non-aqueous biocatalysis by their formulation with excipients. His students have shown, for example, that enzyme activity in organic solvents can be improved nearly 30,000-fold by including simple nonbuffer salts in the lyophilized enzyme. The group has also shown via deuterium NMR measurements that increases in enzyme-bound water mobility mediated by the presence of certain excipients act as a molecular lubricant that alters enzyme flexibility in a manner functionally similar to temperature. Greater flexibility may permit a larger degree of local transition-state mobility, reflected by a larger entropy of activation, for the salt-activated enzyme as compared with the salt-free enzyme. This increased mobility contributes to the dramatic increases in biocatalyst activity. Parallel studies of enzymes activated by solubilization show that the stabilization of the catalytic transition state plays just as important a role in activation in those formulations. People Paul Hudson, Michael Liszka Representative Papers Enzyme Catalysis |