AVS 50th International Symposium
    Surface Science Thursday Sessions
       Session SS3-ThM

Paper SS3-ThM1
Effect of Atomic Polarization on Adsorption on Ferroelectric Surfaces: BaTiO@sub 3@ (100)

Thursday, November 6, 2003, 8:20 am, Room 328

Session: Oxide Structure, Growth, and Defects
Presenter: J. Garra, University of Pennsylvania
Authors: J. Garra, University of Pennsylvania
D.A. Bonnell, University of Pennsylvania
Correspondent: Click to Email
Ferroelectric surfaces have become the focus of recent interest as templates for directed assembly and as thin film devices, yet the surface properties are largely unknown. It has been shown, however, that the local chemical reactivity on ferroelectric surfaces depends on the orientation with which the polarization vector intersects the surface. For example photo reduction (electron donation) occurs over domains with positive surface termination, while photo oxidation (hole donation) occurs over domains with negative surface termination. In order to determine how atomic polarization affects reaction mechanisms, we compare LEED and TPD measurements of desorption from BaTiO@sub 3@ (100) single crystals. Samples are poled in UHV above the Curie temperature and cooled in the electric field in order to achieve homogeneous and predefined polarization orientation before adsorption. Domain structure is confirmed with Piezo Force Microscopy. Water, methanol, and ammonium are used as probe molecules. Adsorbate bond energies above and below the ferroelectric-to-paraelectric phase transition will be discussed in the context of the magnitude of local electric fields.