Neutron scattering as a technique for the study of hydrogen in metals

Neutron scattering techniques are very powerful in studies of the properties of hydrogen atoms either as interstitials in a metal or as constituents of a compound. Detailed information on structural and dynamical properties can be obtained on an atomic scale. The spatial range of a measurement is typically 0.1 A to 100 A, and the dynamical range is 10-10 sec to 10-14 sec. The neutron scattering cross-sections of the two isotopes of hydrogen, the proton and the deuteron, are very different (see discussion below), so one can obtain complementary information on the structural and dynamical properties of a given hydrogen system by studying both hydrided and deuterated systems. The third isotope of hydrogen, tritium, has neutron cross-sections that differ from both the proton and the deuteron. However, because of the radioactivity of tritium, only very few tritium systems have been studied. Neutron scattering cross-sections are discussed, and a short description of various types of instruments is presented. A few examples of results are also discussed