Title

Interaction of hydrogen with the Ag(110) surface

Document Type

Article

Publication Date

1-1-1993

Abstract

The interaction of atomic and molecular hydrogen with the (110) surface of silver has been studied using electron-energy-loss spectroscopy, thermal desorption spectroscopy, low-energy electron diffraction (LEED), and work-function measurements. No evidence for associative or dissociative chemisorption of H2 is observed at the substrate temperatures investigated (90 K). However, at 100 K, atomic hydrogen bonds in the [1 1 0] troughs of the surface in tilted-trigonal sites. As a function of concentration, a sequence of lattice-gas superstructures is observed with LEED including (1×4), (1×3), (2×6), and (2×2) patterns. At saturation coverage, the work function increases by 0.22 eV. However, this phase is metastable; upon annealing, hydrogen desorption is accompanied by an irreversible transition to a new bonding geometry in which LEED shows a dim (1×2) superstructure. The desorption of molecular hydrogen is characterized by two overlapping peaks centered at 155 K [6.9 kJ/mol] and 180 K [9.9 kJ/mol] which obey first- and second-order kinetics, respectively. Various structural models and hydrogen site assignments are discussed in comparison with data for similar systems. © 1993 The American Physical Society.

Publication Source (Journal or Book title)

Physical Review B

First Page

14436

Last Page

14446

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