The structures of adsorbed bromine on the Ag(111) electrode at different ap
plied potentials have been studied by in situ X-ray absorption fine structu
re (XAFS) spectroscopy. The bromine coverage was estimated by the Br K-edge
jump height as a function of the electrode potential. It turned out that t
he coverage does not change in passing through a characteristic peak appear
ing at 0.05 V (versus Ag \ AgCl) in the cyclic voltammogram (CV). Analysis
of the Br K-EXAFS spectra just below the CV peak gave the Br-Ag bond distan
ce of 2.72 +/- 0.05 Angstrom, while the spectra above the peak revealed the
presence of two different Br-Ag bonds with 2.74 +/- 0.05 and 2.80 +/- 0.05
Angstrom distances. These results suggest that a drastic surface reconstru
ction takes place at the characteristic CV peak without changing the surfac
e Br density. (C) 2000 Elsevier Science B.V. All rights reserved.