The surface science of titanium dioxide

The surface and materials science of tin oxide

The Interaction of Water with Solid Surfaces: Fundamental Aspects Revisited

Surface Science Studies of the Photoactivation of TiO2New Photochemical Processes

Ultrathin metal films and particles on oxide surfaces: structural, electronic and chemisorptive properties

One of the most successful ways of inducing enantioselectivity in a heterogeneous catalytic system is by the adsorption of chiral “modifier” molecules on the reactive metal surface. However, little is known about the nature of the active sites present on the modified metal surface and how such modifiers bestow chirality to an achiral metal surface. In this paper we report the behavior of R,R-tartaric acid adsorption on a Cu(110) surface using high-resolution surface analytical techniques. R,R-Tartaric acid is known to be an extremely successful modifier molecule for the enantioselective hydrogenation of methyl acetoacetate, the simplest β-keto ester, to the R-enantiomer of the product molecule methyl 3-hydroxybutyrate. A combination of low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), and Fourier transform reflection−absorption infrared spectroscopy (FT-RAIRS) techniques has allowed us to demonstrate that a complicated adsorption phase diagram exists for this system. A rich vari...

Creating Chiral Surfaces for Enantioselective Heterogeneous Catalysis: R,R-Tartaric Acid on Cu(110)

Effect of stoichiometry on the structure of tio2(110)

Scanning tunneling microscopy (STM) has been used to image the (111) surface of magnetite (${\mathrm{Fe}}_{3}$${\mathrm{O}}_{4}$), following argon-ion bombardment and annealing in ${\mathrm{O}}_{2}$. The (1\ifmmode\times\else\texttimes\fi{}1) hexagonal low-energy electron-diffraction (LEED) pattern obtained from this surface is consistent with a bulk-terminated ${\mathrm{Fe}}_{3}$${\mathrm{O}}_{4}$ (111) surface. STM images show two distinct coexisting surface terminations having identical hexagonal unit-cell dimensions and orientations. We designate these terminations $A$ and $B$. Termination $A$ shows close-packed features separated by 6.1\ifmmode\pm\else\textpm\fi{}0.2 \AA{}, while termination $B$ shows features separated by 3.6\ifmmode\pm\else\textpm\fi{}0.4 \AA{} which are arranged in a honeycomb pattern. The step height from termination $A$ down to termination $B$ is 3.8\ifmmode\pm\else\textpm\fi{}0.5 \AA{}, while that from termination $B$ down to termination $A$ is 0.5\ifmmode\pm\else\textpm\fi{}0.2 \AA{}. A model is proposed which identifies these terminations with the two types of Fe(111) layers found in the bulk ${\mathrm{Fe}}_{3}$${\mathrm{O}}_{4}$ structure. Termination $A$ corresponds to an unreconstructed (111) termination of ${\mathrm{Fe}}_{3}$${\mathrm{O}}_{4}$ that exposes $\frac{3}{4}$ ML of Fe atoms and \textonequarter{} ML of O atoms over a close-packed O layer, with each feature arising from a trimer of Fe atoms capped by an O atom. Termination $B$ corresponds to an unreconstructed (111) termination that exposes \textonehalf{} ML of Fe atoms over a close-packed O layer; each feature is due to a single Fe atom. Ionic and covalent models of surface stability indicate that the atomic arrangement proposed for termination $B$ would be more stable than that for termination $A$.

Structures of Fe 3 O 4 (111) surfaces observed by scanning tunneling microscopy

Scanning tunneling microscopy and low energy electron diffraction have been used to study the $\ensuremath{\alpha}{\ensuremath{-}\mathrm{F}\mathrm{e}}_{2}{\mathrm{O}}_{3}(0001)$ surface in an ultrahigh vacuum. Our results show that this surface can be stabilized by coexisting $\ensuremath{\alpha}{\ensuremath{-}\mathrm{F}\mathrm{e}}_{2}{\mathrm{O}}_{3}(0001)$ and FeO(111) phases, with each phase existing in atomically well-ordered islands of mesoscopic dimensions. Furthermore, the islands themselves are arranged to form a superlattice. The formation of this superlattice can be explained in terms of the lattice mismatch between two types of oxygen sublattices.

Biphase Ordering of Iron Oxide Surfaces.

Scanning tunneling microscopy and first-principles atomic orbital based calculations have been used to study ${\mathrm{TiO}}_{2}(110)1\ifmmode\times\else\texttimes\fi{}2.$ A structure is proposed that resolves the controversy surrounding the surface morphology. Our model is simple, in that it consists only of atoms in their bulk-terminated positions. Theoretical modeling of the images shows an agreement with the experimental data that cannot be achieved even qualitatively for the previously proposed models. Furthermore, a previously unobserved $1\ifmmode\times\else\texttimes\fi{}3$ phase has been imaged that can be simply explained in terms of the model.

P. W. Murray

Papers

Creating Chiral Surfaces for Enantioselective Heterogeneous Catalysis: R,R-Tartaric Acid on Cu(110)

Effect of stoichiometry on the structure of tio2(110)

Structures of Fe 3 O 4 (111) surfaces observed by scanning tunneling microscopy

Biphase Ordering of Iron Oxide Surfaces.

Added row model of TiO 2 ( 110 ) 1 × 2