https://www.surfacesciencewestern.com/wp-content/uploads/2012/01/ass11_biesinger.pdf

Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides: Sc, Ti, V, Cu and Zn

X-ray photoelectron spectroscopy: Towards reliable binding energy referencing

The gas-phase reaction between MoO3-x and H(2)S in a reducing atmosphere at elevated temperatures (800 degrees to 950 degrees C) has been used to synthesize large quantities of an almost pure nested inorganic fullerene (IF) phase of MoS(2). A uniform IF phase with a relatively narrow size distribution was obtained. The synthesis of IFs appears to require, in addition to careful control over the growth conditions, a specific turbulent flow regime. The x-ray spectra of the different samples show that, as the average size of the IF decreases, the van der Waals gap along the c axis increases, largely because of the strain involved in folding of the lamella. Large quantities of quite uniform nanotubes were obtained under modified preparation conditions.

http://science.sciencemag.org/content/sci/267/5195/222.full.pdf

High-Rate, Gas-Phase Growth of MoS2 Nested Inorganic Fullerenes and Nanotubes

Naturally derived cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) are emerging nanomaterials that display high strength, high surface area, and tunable surface chemistry, allowing for controlled interactions with polymers, nanoparticles, small molecules, and biological materials. Industrial production of nanocelluloses is increasing rapidly with several companies already producing on the tons-per-day scale, intensifying the quest for viable products across many sectors. While the hydrophilicity of the nanocellulose interface has posed a challenge to the use of CNCs and CNFs as reinforcing agents in conventional plastics, it is a significant benefit for creating reinforced or structured hydrogel composites (or, when dried, aerogels) exhibiting both mechanical reinforcement and a host of other desirable properties. In this context, this Review describes the quickly growing field of hydrogels and aerogels incorporating nanocelluloses; over 200 references are summarized in comprehensive tables ...

http://pubs.acs.org/doi/pdf/10.1021/acs.chemmater.7b00531

Review of Hydrogels and Aerogels Containing Nanocellulose

Infrared reflection-absorption spectroscopy of adsorbed molecules

Surface Analysis by Auger and X-Ray Photoelectron Spectroscopy

The effects of a change in the chemical environment of an atom in a surface region are manifested in several subtle ways on the measured Auger electron spectra. The first, a shift in the energies of the Auger electrons, is the result of charge transfer and is a measure of the valence state of an atom. Examples of this effect are the oxidation results on refractory metals presented here. It is found that measurable changes are found even for submonolayer coverages of oxygen on an otherwise clean surface. The second main effect is a change in the shape of a complex spectrum, which occurs when some of the electrons involved in this Auger process are valence electrons. The best example of this behavior is that of carbon, and it is found that these complex spectra serve as a fingerprint for the identification of the form of the carbon at a surface. Problems and opportunities for the exploitation of both these effects are discussed, the data included here being illustrative of the usefulness of this type of measurement.

Chemical Effects in Auger Electron Spectroscopy

A study of Ru(0001) and Rh(111) surfaces using LEED and Auger electron spectroscopy

Cerium-based conversion coatings were formed by a spontaneous reaction between a water-based solution containing CeCl3 and aluminum alloy 7075-T6 substrates. Coating performance was evaluated in neutral salt fog according to ASTM B117. Coating microstructure and thickness were observed by scanning electron microscopy (SEM). Coating composition and the cerium oxidation state were characterized using energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) respectively. The morphology and salt fog performance of cerium conversion coatings were affected by pre-treatment of the panel prior to coating. The best pre-treatment consisted of desmutting, degreasing, and acid activation. After immersion in the coating solution for 30 s, Ce-rich deposits formed on the 7075 surface. After 5 min, coatings consisted of Ce-rich particles in a Ce-containing matrix. Immersion times of 5 min or longer produced coatings that could pass published military requirements for conversion coating performance in neutral salt fog. XPS analysis showed that the coatings contained Ce4+.

Characterization of Cerium-based Conversion Coatings for Corrosion Protection of Aluminum Alloys

Corrosion protection is a key requirement for coatings on aircraft as the US Air Force extends the lifetime of its fleet. Coating systems for aluminum have long incorporated chromates in conversion coatings to protect against corrosion, but environmental restrictions require that alternative coating systems be developed. Cerium has been proposed as an alternative to chromate inhibitors, as have several other rare earth elements, because the rare earths behave as cathodic inhibitors in aluminum. Epoxy silicate sol–gels, containing a few wt.% of cerium salts, were investigated as coatings on aluminum alloy 2024-T3. The salts used were cerium(III) chloride, cerium(III) nitrate hexahydrate, and ammonium cerium(IV) nitrate. X-Ray photoelectron spectroscopy (XPS/ESCA) was used to study both the doped sol–gels and reference cerium compounds in order to determine the oxidation state of the cerium at the surface of the sol–gel coatings. No change in the oxidation state of the cerium in the sol–gels was found. Coupled with electrical impedance spectroscopy measurements, the incorporation of cerium into sol–gels seems promising for future corrosion protection of aluminum 2024-T3.

John T. Grant

Papers

Surface Analysis by Auger and X-Ray Photoelectron Spectroscopy

Chemical Effects in Auger Electron Spectroscopy

A study of Ru(0001) and Rh(111) surfaces using LEED and Auger electron spectroscopy

Characterization of Cerium-based Conversion Coatings for Corrosion Protection of Aluminum Alloys

An XPS study of cerium dopants in sol–gel coatings for aluminum 2024-T3