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Photoemission electron microscopy performed on a well-prepared surface of BaTiO3 reveals the persistence of surface domains at temperatures well above the bulk Curie temperature. Their patterns follow the ferroelectric domain structure observed at 300 K. The contrast between formerly outward polarized domains and in-plane polarized domains is preserved across the transition, while the contrast of inward polarized domains changes sign. The work functions of different possible structures are compared by first-principles calculations. The domain contrast in photoemission above the bulk Curie temperature is associated with a remaining tetragonal distortion of the topmost unit cells which is stabilized by an ionic surface relaxation.

The monolayer of ␣-sexithiophene on Ag͑001͒ has been studied by scanning tunneling microscopy and low-energy electron diffraction. Upon deposition at room temperature four well-ordered and commensurate molecular structures have been identified where the molecules adsorb flat lying with their long axis parallel to the ͓110͔ and ͓110͔ high-symmetry directions. Whereas three structures consist of straight molecules in alltrans configuration, one long-range ordered structure is observed where all molecules have undergone a trans-cis isomerization process between the second and third thiophene ring.