P411
In situ ATR-IR Study of Water on Gold Electrode Surfaces
Masayuki Futamata
JRCAT-NAIR
We have been studying the ATR-IR spectroscopy to elucidate the interaction
of water with coadsorbed ions at the electrode surface. This method has
various advantages such as surface sensitivity, selectivity and relevance
to quite smooth metal surfaces. At least three distinct water species (I, II, III)
were observed at the Au surface during adsorption/desorption process of
halide ions. For instance, water (I) has quite high frequency for the
O-H stretching band with an extremely narrow band width, attributed to
water molecules solvated to halide ions. Different halide ion adsorbs
and desorbs at different potentials corresponding to difference in hydration
energy. Nevertheless, the water (I) gives quite similar frequencies at
the Au surface. Furthermore, the frequency of the water (I) band is slightly
shifted by substitution of the counter cation. Details of the spectral
features from the surface water will be described in more detail including
the background shift and the first layer effect like Stark effect and back-
donation upon adsorption.
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