http://experimentationlab.berkeley.edu/sites/default/files/AFMImages/butt_AFM.pdf

Force measurements with the atomic force microscope: Technique, interpretation and applications

5.1. Nanoalloys of Group 11 (Cu, Ag, Au) 865 5.1.1. Cu−Ag 866 5.1.2. Cu−Au 867 5.1.3. Ag−Au 870 5.1.4. Cu−Ag−Au 872 5.2. Nanoalloys of Group 10 (Ni, Pd, Pt) 872 5.2.1. Ni−Pd 872 * To whom correspondence should be addressed. Phone: +39010 3536214. Fax:+39010 311066. E-mail: ferrando@fisica.unige.it. † Universita di Genova. ‡ Argonne National Laboratory. § University of Birmingham. | As of October 1, 2007, Chemical Sciences and Engineering Division. Volume 108, Number 3

Nanoalloys: From Theory to Applications of Alloy Clusters and Nanoparticles

Recent advances in catalysis have made the incorporation of fluorine into complex organic molecules easier than ever before, but selective, general and practical fluorination reactions remain sought after. Fluorination of molecules often imparts desirable properties, such as metabolic and thermal stability, and fluorinated molecules are therefore frequently used as pharmaceuticals or materials. But the formation of carbon-fluorine bonds in complex molecules is a significant challenge. Here we discuss reactions to make organofluorides that have emerged within the past few years and which exemplify how to overcome some of the intricate challenges associated with fluorination.

/pdf/catalysis-for-fluorination-and-trifluoromethylation-4ahg2wnf74.pdf

Catalysis for fluorination and trifluoromethylation

Solid films are usually metastable or unstable in the as-deposited state, and they will dewet or agglomerate to form islands when heated to sufficiently high temperatures. This process is driven by surface energy minimization and can occur via surface diffusion well below a film's melting temperature, especially when the film is very thin. Dewetting during processing of films for use in micro- and nanosystems is often undesirable, and means of avoiding dewetting are important in this context. However, dewetting can also be useful in making arrays of nanoscale particles for electronic and photonic devices and for catalyzing growth of nanotubes and nanowires. Templating of dewetting using patterned surface topography or prepatterning of films can be used to create ordered arrays of particles and complex patterns of partially dewetted structures. Studies of dewetting can also provide fundamental new insight into the effects of surface energy anisotropy and facets on shape evolution.

Solid-State Dewetting of Thin Films

The surface area is one of the most important quantities for characterizing novel porous materials. The BET analysis is the standard method for determining surface areas from nitrogen adsorption isotherms and was originally derived for multilayer gas adsorption onto flat surfaces. Metal-organic frameworks (MOFs) are a relatively new class of crystalline, porous materials that have been shown to exhibit very large BET surface areas. These materials are microporous and possess surfaces that are far from flat. In some MOFs, adsorption occurs through a pore-filling mechanism rather than by layer formation. Thus, it is unclear whether BET surface area numbers reported for these materials are truly meaningful. Given the standard practice of reporting BET surface areas for novel porous materials, a critical test of the BET method is much needed. In this work, grand canonical Monte Carlo simulations were used to predict adsorption isotherms for nitrogen in a series of MOFs. The predicted isotherms were used as pseudoexperimental data to test the applicability of the BET theory for obtaining surface areas of microporous MOFs. BET surface areas calculated from the simulated isotherms agree very well with the accessible surface areas calculated directly from the crystal structures in a geometric fashion. In addition, the surface areas agree well with experimental reports in the literature. These results provide a strong validation that the BET theory can be used to obtain surface areas of MOFs.

Applicability of the BET method for determining surface areas of microporous metal-organic frameworks.

Strong friction anisotropy is found when the twofold surface of an atomically clean aluminum-nickel-cobalt quasicrystal slides against a thiol-passivated titanium-nitride tip. Friction along the aperiodic direction is one-eighth as much as that along the periodic direction. This anisotropy, which is about three times as large as the highest value observed in anisotropic crystalline surfaces, disappears after the surface is oxidized in air. These results reveal a strong connection between interface atomic structure and the mechanisms by which energy is dissipated, which likely include electronic or phononic contributions, or both.

https://science.sciencemag.org/content/sci/309/5739/1354.full.pdf

High Frictional Anisotropy of Periodic and Aperiodic Directions on a Quasicrystal Surface

The atomic structure of the fivefold symmetric quasicrystal surface of A${\mathrm{l}}_{70}$P${\mathrm{d}}_{21}$M${\mathrm{n}}_{9}$ was investigated by means of a dynamical low energy electron-diffraction analysis. Approximations are developed to address the high structural complexity of quasicrystals, yielding average layer-by-layer structural and compositional information. A mix of several relaxed bulklike terminations is found, consistently favoring dense Al-rich outermost atomic layers. These results can be understood in terms of principles known to govern surface structures of simpler, crystalline metals.

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1072&context=chem_pubs

Structural Analysis of the Fivefold Symmetric Surface of the Al70Pd21Mn9 Quasicrystal by Low Energy Electron Diffraction

Photoelectron spectra of a fivefold quasicrystalline alloy ${\mathrm{Al}}_{70}$${\mathrm{Pd}}_{21}$${\mathrm{Mn}}_{9}$ and a related cubic alloy ${\mathrm{Al}}_{60}$${\mathrm{Pd}}_{25}$${\mathrm{Mn}}_{15}$ reveal two noteworthy features. The first is that the Pd $3d$ lines fall at binding energies which are 2.2 eV higher than in pure Pd. A similar shift is observed for Pd in other alloys. The second noteworthy feature is that the Mn $2{p}_{\frac{3}{2}}$ line is very sharp in the quasicrystal. Fitting the experimental peaks with a Doniach-Sunjic line shpae suggests that the position and density of Mn states near ${E}_{F}$ is very sensitive to the structural and/or chemical environment of Mn in the alloys, and that this accounts for the shape of the $2{p}_{\frac{3}{2}}$ Mn line. The sharpness of the Mn line may be a fingerprint of the quasicrystalline phase within the AlPdMn family.

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1092&context=physastro_pubs

Photoelectron spectra of an Al70Pd21Mn9 quasicrystal and the cubic alloy Al60Pd25Mn15

The atomic structure of the fivefold symmetric quasicrystal surface of icosahedral AlPdMn has been investigated by means of a dynamical low-energy-electron diffraction (LEED) analysis. Approximations were developed to make the structure of an aperiodic, quasicrystalline surface region accessible to LEED theory. A mix of several closely similar, relaxed, bulklike lattice terminations is favored, all of which have a dense Al-rich layer on top followed by a layer with a composition of about 50% Al and 50% Pd. The interlayer spacing between these two topmost layers is contracted from the bulk value by 0.1 \AA{}, to a final value of 0.38 \AA{}, and the lateral density of the two topmost layers taken together is similar to that of an Al(111) surface. The LEED structural result is qualitatively consistent with data from ion scattering spectroscopy, which supports an Al-rich termination.

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1063&context=chem_pubs

Cynthia J. Jenks

Papers

High Frictional Anisotropy of Periodic and Aperiodic Directions on a Quasicrystal Surface

Structural Analysis of the Fivefold Symmetric Surface of the Al70Pd21Mn9 Quasicrystal by Low Energy Electron Diffraction

Photoelectron spectra of an Al70Pd21Mn9 quasicrystal and the cubic alloy Al60Pd25Mn15

Fivefold surface of quasicrystalline AlPdMn: Structure determination using low-energy-electron diffraction

Oxygen adsorption on a single-grain, quasicrystal surface