Chemisorption of hydrogen on the Ag(111) surface

Journal Article · Fri Jul 01 00:00:00 EDT 1994 · Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (United States)

DOI:https://doi.org/10.1116/1.579147· OSTI ID:7086529

Lee, G; Sprunger, P T ^[1]; Okada, M ^[2]; Poker, D B; Zehner, D M ^[3]; Plummer, E W ^[4]

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1. Department of Physics, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6396 (United States)
2. Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996 (United States)
3. Sold State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6057 (United States)
4. Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996 (United States) Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6057 (United States)

The interaction of atomic hydrogen/deuterium with the Ag(111) surface was investigated with high-resolution electron loss spectroscopy (HREELS), thermal desorption spectroscopy, low-energy electron diffraction (LEED) and the results correlated with the work function change and an absolute coverage measurement. Dissociation of molecular hydrogen is an activated process on Ag(111) but atomic hydrogen chemisorbs and at a temperature of [similar to]185 K, recombines and desorbs as H[sub 2]. Upon the adsorption of atomic hydrogen at 100 K, a sharp (2[times]2) LEED pattern is observed in the coverage range 0.25[similar to]0.5 ML and is followed by combined (2[times]2)+(3[times]3) patterns with an increase in coverage of 0.1 ML. The saturation coverage is determined to be [Theta][sub sat]=0.6[plus minus]0.1 ML. In contrast to other H/fcc(111) systems, the intensities of the fractional order diffraction beams are quite large, suggesting an H-induced reconstruction. The work function increases monotonically with H-exposure to a maximum value of [Delta][phi][sub max]=+0.32 eV at saturation. Specular HREELS vibrational data show a single loss at 106 meV for hydrogen (76 meV for deuterium), similar to the normal vibrational mode observed for the H/Ag(110) system. A rather low activation energy (8.7[plus minus]1.0 kcal/mol) for recombinative desorption is obtained from the low coverage thermal desorption spectra ([Theta][lt]0.1 ML).

• DOE Contract Number: AC05-84OR21400
• OSTI ID: 7086529
• Journal Information: Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (United States), Vol. 12:4; ISSN 0734-2101
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
DEUTERIUM
CHEMISORPTION
HYDROGEN
SILVER
SORPTIVE PROPERTIES
ACTIVATION ENERGY
DESORPTION
ELECTRON DIFFRACTION
ENERGY-LOSS SPECTROSCOPY
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0065-0273 K
VIBRATIONAL STATES
WORK FUNCTIONS
CHEMICAL REACTIONS
COHERENT SCATTERING
DIFFRACTION
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY
ENERGY LEVELS
EXCITED STATES
FUNCTIONS
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
METALS
NONMETALS
NUCLEI
ODD-ODD NUCLEI
SCATTERING
SEPARATION PROCESSES
SORPTION
SPECTROSCOPY
STABLE ISOTOPES
SURFACE PROPERTIES
TEMPERATURE RANGE
TRANSITION ELEMENTS
360104* - Metals & Alloys- Physical Properties