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Abstract

The coadsorption systemAg(110)-O/H₂O is known to give rise to well defined OH layers in a thermally activated process between 190 and 220 K. In a high resolution EELS study we have found that the (1 × n), n = 3,2 ordered layers produced from the (n × 1), n = 6,4 reconstructed Ag(110)-O surface are characterized by very sharp loss peaks at 277 cm⁻¹ (v(M-OH)) and 3390 cm⁻¹ (v(O-H)). The dominant M-OH loss exhibits essentially the same halfwidth as the specular peak, whereas the OH bending mode at 675 cm⁻¹ is significantly broadened and shows a shoulder at 755 cm⁻¹. The (1 × 1)-OH phase formed from the (2 × 1)-O-reconstructed phase is less stable than the lower coverage OH layers. Such studies may play an important role in understanding the mechanism of this almost unique stoichiometric reaction.