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Determination of Hydrogen(Deuterium) Density Profiles in Thin Metal Films and Multilayers by Neutron Reflection

Published online by Cambridge University Press:  21 February 2011

C. F. Majkrzak
Affiliation:
National Institute of Standards and Technology, Gaithersburg, MD 20899
S. Satija
Affiliation:
National Institute of Standards and Technology, Gaithersburg, MD 20899
O. A. Neumann
Affiliation:
National Institute of Standards and Technology, Gaithersburg, MD 20899
J. J. Rush
Affiliation:
National Institute of Standards and Technology, Gaithersburg, MD 20899
D. Lashmore
Affiliation:
National Institute of Standards and Technology, Gaithersburg, MD 20899
C. Johnson
Affiliation:
National Institute of Standards and Technology, Gaithersburg, MD 20899
J. Bradshaw
Affiliation:
Optoline Associates, Andover, MA 01810
L. Passell
Affiliation:
Optoline Associates, Andover, MA 01810
R. Dinardo
Affiliation:
Brookhaven National Laboratory, Upton, NY 11973
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Abstract

The density of hydrogen in thin films or multilayers of metal hydrides can be inferred from an expansion of the host lattice as measured by conventional x-ray diffraction techniques. However, because hydrogen and deuterium have scattering lengths for neutrons that are comparable to those of most metal nuclei, unlike the corresponding case for x-ray atomic scattering amplitudes, the hydrogen density profile normal to the surface of a flat, thin film can be determined directly from neutron reflectivity measurements. The hydrogen (deuterium) density modulation in an artificial superlattice along the growth direction can also be determined in this manner. The thin film or multilayer host metal material need not even be crystalline. Furthermore, because relatively large, flat single crystal substrates such as Si or quartz are nearly transparent to neutrons, the substrate can serve as the incident medium and the reflectivities of films or multilayers in contact with liquid solutions can be obtained. Thus, in situ studies employing active electrochemical cells, for example, can be performed. In addition to discussing the sensitivity of the method, the results of some neutron reflectivity experiments on metal multilayers and films, electrolytically loaded in situ with deuterium, are reported in this paper.

Type
Research Article
Copyright
Copyright © Materials Research Society 1990

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References

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