Principal Investigator Sylvia Ceyer
We have demonstrated that high resolution electron energy loss spectroscopy, a technique previously believed to be surface sensitive only, can be used to detect the vibrations of species buried in the bulk of the metal. Specifically, we have characterized a H atom embedded in the Ni bulk by a single 800 cm-1 loss feature. This feature, for which an impact scattering mechanism is operable, is identified as an interstitial Ni-H vibration by the similarity of the dependence of its intensity on electron impact energy to the dependence of the electron inelastic mean free path on electron energy. This study, which is described in Phys. Rev. Lett. 67, 927 (1991), represents the first conclusive detection of subsurface vibrations of absorbed species by HREELS.