Joe is an instrument scientist for the Magik Reflectometer at the NCNR, and applies neutron reflectometry, NR, to a variety of disciplines including energy storage and conversion, hydrogen interactions, biology, and magnetic materials, in addition to developing Neutron Reflectometry techniques, instrumentation and sample environments. Neutron reflectometry measures the reflected intensity of a thin monochromatic neutron beam as a function of the grazing incidence angle relative to a flat smooth sample surface. The sample typically consists of layers or coatings with thickness of 1-500nm (either intentionally deposited or as the result of surface or interface reactions). By analyzing NR data, which consists of oscillations in the intensity, one determines a depth profile of the scattering length density in the sample with up to sub-angstrom level precision and accuracy. For neutrons, the scattering length density, which can be determined from the composition, can vary quite significantly for certain isotopes of the same element. For elements with a large isotope difference one can determine an elemental depth profile, label specific layers in the sample, or label specific reactants to determine which contribute to the formation of surface layers. Hydrogen and Lithium are two of many elements with a particularly large isotope effect and which has been utilized in studies of polymers, biological systems, fuel cells and battery materials. Because neutrons can readily penetrate a variety of materials, neutron reflectometry is also ideal for in-situ, in-operando and multimodal measurements.
CREB: Center for Research in Extreme Batteries, Steering Committee
APS GERA Executive Committee