Atomic force microscopy images of MgO 100/and TiO 110/ 2 under water and aqueous aromatic molecule solutions

In situ atomic force microscopy AFM.observations at atomic level of the surface structures of MgO 100.and TiO2 110. under water and aqueous aromatic molecule solutions are reported. Under deionized water the MgO 100.surface showed slow dissolution initiated by pitting, whereas the TiO2 110.surface did not show any surface dissolution. At atomic level, MgO 100.gave AFM images of very low contrast, indicating very small force variations on its surface under aqueous environment. TiO2 110. showed images with rows whose intervals correspond to those of Ti4q rows. Addition of an aqueous ammonium benzoate solution onto MgO 100. surface produced structures attributable to adsorbed molecule overlayers, similar to the ones observed on zeolite surfaces. The TiO2 110.surface under aqueous aromatic solutions gave images similar to those obtained under deionized water, indicating no or very slow adsorption of these molecules on the surface. q1997 Elsevier Science B.V.