Spin polarization of CrO2 at and across an artificial barrier

We report a systematic study of the spin polarization of epitaxial CrO2 films at and across an interface using planar junctions with a superconducting counterelectrode. By chemical modification of the CrO2 surface before the deposition of the superconductor, junctions with a wide range of barrier strength were obtained. Analysis of the conductance data on these junctions, especially under Zeeman splitting of the superconducting density of states, yields consistent, close to full spin polarization for CrO2 regardless of the barrier strength.     

Electrochemical and Spectroscopic Properties of Fly Ash–Polyaniline Matrix Nanorod Composites

Polyaniline (PANI) nanocomposites were prepared with fly ash (FA) either by aging the starting materials (aniline and FA) before oxidative polymerisation or by including poly(styrene sulphonic acid) (PSSA) eliminating the aging step. The aging procedure formed polymer nanotubes that have cross-sectional diameters of 50–110 nm. The procedure involving PSSA produced nanorods and nanofibres composites that have diameters of 100–500 nm and length of up to 10 μm attributed to the presence of metal oxides and silica in FA. The electrochemical analysis of the PANI–PSSA–FA nanorod composites shows three redox couples with formal potentials, , values of 105 mV, 455 mV and 670 mV, and conductance, C, value of 1.21 × 10⁻² S. The UV-Vis spectroscopy of the polymeric nanorod shows absorption maxima at 340 and 370 nm (due to π–π^* transition of the benzoid rings), and 600–650 nm (due to charge transfer excitons of the quinoid structure), which are characteristic of emeraldine base.     

Development of an automated in situ fracture stage for a ToF‐SIMS system

The design philosophy and implementation of an ultra high vacuum (UHV), PC controlled, automated in situ fracture stage for a surface analysis system is described. ToF‐SIMS spectra are shown to illustrate the improvement in spectral quality obtained from micro‐compact tension (CT) tests of polymer matrix fracture surfaces produced using the fracture stage in UHV compared to those obtained from a sample tested at air. This system is flexible in that by changing the capacity of the load cell it is possible to reduce or increase maximum loads as the specimen type and material demands. The stage has been designed with instrumental flexibility in mind, utilising commercial SEM‐stub type sample mounts, and can thus be used for AES/SAM and XPS investigations, as well as ToF‐SIMS analysis, in the authors' laboratory. Copyright © 2008 John Wiley & Sons, Ltd.     

Photo-oxidation of unsaturated ferrocenyl-substituted carboxylic acids

In aqueous solution (pH 9) containing N₂O, the unsaturated acids $\text{trans}$-FcCHCH(CH₂)nCO₂H (n = 0 and 1) and FcCCCO₂H each undergo photo-oxidation, upon illumination with u.v. light of wavelength 240-250 nm, giving dipolar ferricenium species which may be chemically reduced back to the original acids. The mechanism of photo-oxidation, which is inhibited by ethanol, appears to be similar to that previously proposed for saturated ω-ferrocenylalkanoic acids.     

Analysis of the OH bend and stretch region in the vibrational spectrum of water

A method for calculating the infrared absorption spectrum of water in a range of different physical environments is described. Calculations are based on Monte Carlo simulations together with local-mode analyses of the H₂O vibrations. Results for liquid water and amorphous ice show clearly that the major features of the OH stretching motions are reproduced with good accuracy.     

High speed analysis of underivatized drugs by gas chromatography–mass spectrometry

The technique of choice for many types of forensic drug confirmations is gas chromatography/mass spectrometry (GC/MS). Significant amounts of analytical time can be involved in a GC/MS run. The use of a 0.1 mm i.d. fused silica capillary column with hydrogen carrier gas can significantly increase the speed of an analysis without sacrificing resolution. Nanogram levels of underivatized drugs, from amphetamine to strychnine, can be eluted in less than twelve minutes. The multitasking system permits data acquisition, while performing data reduction on the previous run.     

A guide for the meaningful surface analysis of wood by XPS and ToF-SIMS

The surface analysis of wood and wood products is becoming increasingly important for reasons ranging from the investigation of molecular constituents through to the optimization of industrial processes. As with any natural product, wood analysis is not straightforward, and this review aims to provide guidance for the successful surface analysis of wood by XPS and ToF-SIMS. Through example experiments, three themes are addressed relevant to obtaining meaningful results: considerations related to heterogeneity in the composition of wood (e.g., growth rings); the impact of the chemical removal of minor wood components known as extractives, and whether such a process is necessary; and the potential for misleading or erroneous results as a result of contamination occurring during sample preparation. In addition to discussing successful sample preparation approaches, the important role to be played by MVA in surface analysis is emphasized, particularly in the analysis of ToF-SIMS data. Examples of ToF-SIMS/MVA are provided that highlight the identification of contamination in sample preparation, the quantification of wood composition in terms of cellulose and lignin, and the indication of age of softwood samples. Through consideration of the complexities that influence wood surface analysis, the design and interpretation of consequential experiments become easier and more accurate.     

Coupled-cluster study of isomers of H2SO2

A theoretical study has been made on six isomers of H2SO2 using coupled-cluster singles and doubles with noniterative triple excitations (CCSD(T)). The isomers studied are sulfoxylic acid (S(OH)2; C2 and Cs conformers), sulfinic acid (HS(=O)OH; 2 C1 conformers), dihydrogen sulfone (H2SO2; C2v), sulfhydryl hydroperoxide (HSOOH; C1), thiadioxirane (Cs), and dihydrogen persulfoxide (H2SOO; Cs). Molecular geometries, harmonic vibrational frequencies, and infrared intensities of all species were obtained using the CCSD(T) method and the 6-311++G(2d,2p) basis set. All aforementioned species were found to be local minima, with the exception of thiadioxirane, which has one imaginary frequency. A prior possible infrared observation of sulfinic acid was reassessed on the basis of the present data. In agreement with previous MP2 results, the present CCSD(T) data provide support for at most 4 of the 8 observed frequencies. The CCSD(T) frequencies and intensities should be of assistance in future identification of H2SO2 isomers by vibrational spectroscopy. Relative energies were calculated using the CCSD(T) method and several larger basis sets. As found previously, the lowest energy species is C2 S(OH)2, followed by Cs S(OH)2, HS(=O)OH, H2SO2, HSOOH, thiadioxirane, and H2SOO. Expanding the basis set significantly reduces the relative energies of HS(=O)OH and H2SO2. The CCSD(T) method was used with extended basis sets (up to aug-cc-pV(Q+d)Z) and basis set extrapolation in two reaction schemes to calculate the DeltaH degrees t (25 degrees C) of C2 S(OH)2. The two reaction schemes gave -285.8 and -282.7 kJ mol-1, which are quite close to a prior theoretical estimate (-290 kJ mol-1).     

Aryl trihydroxyborates: easily isolated discrete species convenient for direct application in coupling reactions

A conceptually and practically simple alternative approach to the use of arylboron species as the organometallic component in cross-coupling processes is described whereby trihydroxyborate salts are isolated and directly employed. The protocol derives practical benefit from the ease and convenience of the isolation and subsequent use of the discrete borate salts, eliminates the need for additional base, and aids the use of correct reaction stoichiometry.