THE ELECTROREFLECTION SPECTRA OF ANODICALLY OXIDIZED IRIDIUM AND ADSORPTION OF WATER

The potential dependences of energy E and intensity of bands in the el ectroreflection (ER) spectra of hydrated IrO2 films on iridium in sulf uric-acid and alkaline solutions are studied. The mechanism for genera tion of ER spectra by electromodulation of optical polarizability of t he water layer adsorbed on the surface and in the surface layers of an IrO2 him is suggested. The mechanism helps explain the nonmonotonic p otential dependence of the energy of optical transitions involving cha rge transfer from water molecules to vacant states of the 5d(e(g)) and 5d(t(2g)) IrO2 bands and the nature of sign inversion in the real par t of ER observed at some potentials. The mechanism presumably contribu tes to the electrochromic effect of IrO2 films.