The adsorption of hydrogen on Ru(1 1 2 1)

HREELS and TDS results are presented for hydrogen adsorption on Ru(1 1 2 1) at 90 K. Three distinct adsorption states were separated both from TDS and HREELS. These α, β and γ states are characterized by desorption temperatures of 115, 175–280, 345 K. The according vibrational energies are (42, 95 meV), (64, 115, 160 meV) and (62, 92, 145 meV). By comparison with literature data and taking into account the site symmetries, these states are assigned to fourfold and threefold symmetric sites, respectively.