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Accelerator Seminar


"Novel Applications of Spectroscopy to Study Hydrogen"

John Paul Wallace,
Casting Analysis Corporation,
Weyers Cave, VA




Iron and Niobium are two BCC metals with characteristic that are not too dissimilar with respect to hydrogen diffusion rate and makes the binary relatively easy to study.  Hydrogen activity near free surfaces in niobium could lower the maximum H field which will quench superconductivity and in iron lead to embrittlement and interesting field switching characteristics.  Recently we found a new spectroscopic tool to monitor the interaction of dissolved hydrogen with internal EM fields at frequencies below the infrared.  This new tool gives a measure of the transition strength caused by the local lattice distortion on interstitial hydrogen and the associated spin state associate with the hydrogen screening.  This new tool in additions to surface reflection IR spectroscopy, positron annihilation, X-ray lattice parameter measurements and inverse multi frequency eddy current profiling of conductivity allows one to gain knowledge of hydrogen’s concentration in the oxide, near surface and bulk as well as isolating hydride formation and their magnetic character. These tools allow one to determine a functional phase diagram for the three regions of the metal-hydrogen system when temperature, concentration, grain orientation and stress state are varied.



Wednesday, December 3, 2008

2:00 - 3:00 p.m.

ARC, Room 231/233

Talk Slides: (Slides)

For more information, please contact Dr. Alex Bogacz or Anne-Marie Valente.