Fluctuation of acetate ions in the (2 x 1)-acetate overlayer on TiO2(110)-(1 x 1) observed by noncontact atomic force microscopy

Fluctuating molecules of acetate ions in the (2 x 1)-acetate overlayer on T iO2(110)-(1 x 1) were observed by noncontact atomic force microscopy. Each acetate ion adsorbed on its stable site was observed as bright round protru sion ordered in a (2 x 1) periodicity. On the other hand, acetate ions at a boundary between domains with different phases along the [001] direction m oved along the [001] direction during scanning and gave fragmentary images. As a result, unstable regions for acetate ions were formed at domain bound aries. This phenomenon was explained in terms of repulsive and attractive i nteractions worked between acetate ions and hydroxyl hydrogen atoms, which are formed by dissociative adsorption of acetic acid. (C) 2000 Elsevier Sci ence B.V. All rights reserved.