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Issues concerning the surface-normal structure liquid Hg-Au alloys near a room temperature solubility limit of 0.14% atom % Au in Hg by the use of synchroton X-ray reflectivity are discussed.

We report a detailed optical investigation of the wetting phenomena in fluid metalrich KxKCl1-x solutions for temperatures up to 820 °C and x≥0.86. To this end the fluid sample–sapphire interface has been probed by second harmonic generation (SHG) with continuous variation of temperature T at various x. At coexistence a wetting transition near Tw≊500 °C is signaled by a clear change in the temperature dependence of the SH intensity. This observation is in agreement with previous ellipsometric measurements. The precise location of the transition in these systems is strongly influenced by the presence of oxygen impurities segregating at the interface. This is manifested in a strong enhancement of the SH signal in the vicinity of 450 °C. In the homogeneous metal-rich phase the SH intensity shows a pronounced maximum as a function of temperature for T>=Tw. The occurrence of these maxima is explained consistently by assuming a salt-rich microscopic wetting film in between the metallic bulk fluid and the sapphire window whose thickness changes from thick to thin with increasing temperature. The line connecting these maxima positions in the x–T plane exhibits all the characteristics of a prewetting line. In particular, it is curved away from the coexistence curve as has been predicted theoretically for systems with screened Coulombic interactions, but is found here for the first time experimentally. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report x-ray reflectivity measurements of liquid mercury between -36 °C and +25 °C. The surface structure can be described by a layered density profile convolved with a thermal roughness σT. The layering has a spacing of 2.72 Å and an exponential decay length of 5.0 Å. Surprisingly, σT is found to increase considerably faster with temperature than the √T behavior predicted by capillary wave theory, in contrast with previous measurements on Ga and dielectric liquids., Engineering and Applied Sciences

The oxidation of liquid-gallium surfaces has been investigated with surface x-ray scattering techniques. By exposing the liquid-metal surface at room temperature to doses on the order of 180 L of oxygen where 1 L=10\(^{-6}\) Torr s, a gallium oxide film with a well-defined thickness of \(\sim\)5 Å readily forms. The oxide thickness and roughness of the liquid/oxide and oxide/vapor interfaces do not change with oxygen dosage up to 1600 L nor with temperature up to 573 K. This is in contrast to what is observed for the bare liquid-Ga surface, which is roughened significantly by thermally excited capillary waves with temperatures up to only 443 K. This is a good indication that the oxide layer provides rigidity to the liquid surface and is likely a solid; grazing-incidence measurements suggest that the film is amorphous or poorly crystallized. Based on comparisons with known crystal structures, models are suggested for the atomic arrangements in the gallium oxide layer and its interface with the underlying liquid., Engineering and Applied Sciences

We report x-ray reflectivity (XR) and small-angle off-specular diffuse-scattering (DS) measurements from the surface of liquid indium close to its melting point of 156°C. From the XR measurements we extract the surface structure factor convolved with fluctuations in the height of the liquid surface. We present a model to describe DS that takes into account the surface structure factor, thermally excited capillary waves, and the experimental resolution. The experimentally determined DS follows this model with no adjustable parameters, allowing the surface structure factor to be deconvolved from the thermally excited height fluctuations. The resulting local electron-density profile displays exponentially decaying surface-induced layering similar to that previously reported for Ga and Hg. We compare the details of the local electron-density profiles of liquid In, which is a nearly free-electron metal, and liquid Ga, which is considerably more covalent and shows directional bonding in the melt. The oscillatory density profiles have comparable amplitudes in both metals, but surface layering decays over a length scale of 3.5±0.6Å for In and 5.5±0.4Å for Ga. Upon controlled exposure to oxygen, no oxide monolayer is formed on the liquid In surface, unlike the passivating film formed on liquid gallium., Engineering and Applied Sciences

Recent decisions by the highest courts in the US in regard to written description and enablement as well as parallel restrictions previously established in Europe emphasize that applicants in the fields of chemistry/pharma/life sciences should strive to include as many examples, data, and guidance about how to extrapolate from the example(s) in the description. This holds in particular whenever a broad genus and/or functional features is/are to be protected. It is important to keep in mind that these data and this guidance must be disclosed in the application at the time of filing. Data collected at a later stage can only be used to further support data and evidence already present in the application as filed.

The x-ray absorption fine structure (XAFS) of colloidal Au and Au/Ag nanoparticles (3.5nm and 20nm mean diameter) in an aqueous solution has been investigated. Size dependent alloying was observed upon deposition of Ag on Au core. Ag forms distinct layers around the 20 nm Au nanoparticles. In contrast, random mixing is found for Ag deposited on 3.5nm Au particles.