Abstract
The adsorption of hydrogen on the Mo(110) surface has been investigated by both low-energy electron diffraction (LEED) and high-resolution electron energy loss spectroscopy (HREELS). Results fall into three regimes. For low coverages, the LEED pattern observed remains (1 × 1), similar to the clean surface. At hydrogen coverages near 0.5 ML, a substrate reconstruction alters the observed pattern to (2 × 2). For higher coverages, fractional-order diffraction beams are extinguished, leaving a (1 × 1) pattern. Two vibrational peaks are observed in HREELS spectra for both low-and high-coverage regimes at loss energies of 88 and 136 meV, and at 99 and 152 meV, respectively. A quasi-trigonal adsorption site is consistent with the vibrational energies and diffraction patterns observed at low and saturation coverages. At intermediate coverages, a vibrational peak with differing symmetry indicates the occupation of a long bridge-site during the transition from (2 × 2) to the hydrogen-saturated (1 × 1). No evidence is found for the hydrogen "liquid" phass reported by Balden et al. [Phys. Rev. Lett. 73 (1994) 854] for H/W(110); consequently this phase is not responsible for the giant phonon anomalies observed in both systems. Published by Elsevier Science B.V.
Original language | English |
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Pages (from-to) | 145-152 |
Number of pages | 8 |
Journal | Surface Science |
Volume | 373 |
Issue number | 2-3 |
DOIs | |
State | Published - Mar 1 1997 |
Funding
The authors would like to thank G.W. Ownby for preparation of the sample, and appreciate discussions with E.W. Plummer. This work was supported by the Division of Material Science, US Department of Energy, under contract DE-AC05-96OR22464 with Lockheed Martin Energy Research Corporation, and the Japanese Government through the NEDO International Joint Research Grant Program.
Keywords
- Chemisorption
- Electron energy loss spectroscopy
- Hydrogen
- Low energy electron diffraction
- Low index single crystal surfaces
- Molybdenum
- Surface relaxation and reconstruction