Precise measurement of electronic gJ value of helium,gJ(4He,23S1)

We report the measurement of $\text{g}{}_{\mathrm{J}}\text{(}{}^4\text{He,2}{}^3\text{S}{}_1\text{)}\text{g}{}_{\mathrm{J}}\text{(}{}^{85}\text{Rb}\text{,5}{}^2\text{S}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{)}$ by the atomic beam magnetic reson ance method using separated oscillating fields, and hence the determination $\text{g}{}_{\mathrm{J}}\text{(}{}^4\text{He,2}{}^3\text{S}{}_1\text{)}\text{g}{}_{\mathrm{J}}\text{(H,1}{}^2\text{S}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{)}\text{? 1? (23.19±0.07) × 10}{}^{\mathrm{?6}}$, which agrees with theory and with other less precise recent measurements.     

An investigation of metal/GaAs(100) interfaces by deep level transient spectroscopy

In this work we investigate the ability of DLTS to detect the presence of interface states at metal/GaAs(100) (n-type) interfaces where the semiconductor surface has been prepared by two different procedures. A correlation is observed between the magnitude of the ideality parameter determined from the current-voltage (I-V) characteristic of the diode and presence in the DLTS spectrum of a feature attributable to interface states. Schottky diodes have been fabricated with both gold and iron contacts which exhibit near ideal behaviour (n<1.1). No interface states were detected by DLTS on either of these diodes. However, diodes fabricated on oxidised GaAs surfaces, with higher idealities (1.5 <n < 2), exhibit additional electron trap levels in the DLTS spectrum. For the case of iron, a deep level of activation energy 0.55 eV is observed in the conventional reverse bias pulse sequence mode of DLTS operation. In addition, for both gold and iron diodes, a spectral feature which can be attributed to a broad distribution of interface states within the deplation region is observed during a forward bias pulse sequence.     

Thermodynamics for Coulomb systems: A problem at vanishing particle densities

In this paper I combine techniques recently developed by Charles Fefferman with the well-known methods of Joel Lebowitz and Elliott Lieb to resolve some technical problems left unsettled by Lebowitz and Lieb's fundamental 1972 paper The constitution of matter: Existence of thermodynamics for systems composed of electrons and nuclei.     

Low-level otoacoustic emissions may predict susceptibility to noise-induced hearing loss

In a longitudinal study with 338 volunteers, audiometric thresholds and otoacoustic emissions were measured before and after 6 months of noise exposure on an aircraft carrier. While the average amplitudes of the otoacoustic emissions decreased significantly, the average audiometric thresholds did not change. Furthermore, there were no significant correlations between changes in audiometric thresholds and changes in otoacoustic emissions. Changes in transient-evoked otoacoustic emissions and distortion-product otoacoustic emissions were moderately correlated. Eighteen ears acquired permanent audiometric threshold shifts. Only one-third of those ears showed significant otoacoustic emission shifts that mirrored their permanent threshold shifts. A Bayesian analysis indicated that permanent threshold shift status following a deployment was predicted by baseline low-level or absent otoacoustic emissions. The best predictor was transient-evoked otoacoustic emission amplitude in the 4-kHz half-octave frequency band, with risk increasing more than sixfold from approximately 3% to 20% as the emission amplitude decreased. It is possible that the otoacoustic emissions indicated noise-induced changes in the inner ear, undetected by audiometric tests. Otoacoustic emissions may therefore be a diagnostic predictor for noise-induced-hearing-loss risk.     

The electronic and magnetic properties of the 3d transition metal intercalates of TiS2

The introduction of 3d transition metals (M) into the van der Waals gaps between the weakly coupled layers of transition metal dichalcogenides TX₂ (T:transition metal, X:chalcogen) produces an interesting family of intercalation compounds, M _x TX₂, the physical properties of which are different from those of the host TX₂ matrix because of ‘host-guest’ interactions. In this article we shall review the salient features of the M _x TiS₂ family with the simple 1T-CdI₂ type layered structure, which have been extensively studied by structural, transport, specific heat and lattice dynamic, magnetic and photoemission spectroscopic measurements. In contrast with the previously reported series of intercalation complexes of the Group V transition metal dichalcogenides, a characteristic of the M _x TiS₂ materials is strong hybridisation between the guest atom M 3d orbitals and the host Ti 3d and S 3p orbitals, leading to changes in the Fermi energy E _F of the conduction band, the density of states at E _F and various types of magnetic orderings. These properties are understood in terms of an itinerant electron or band picture for the intercalant, rather than a rigid band or localised model.     

The use of macroscopic modelling of intermetallic phases in aluminium alloys in the study of ferricyanide accelerated chromate conversion coatings

Chromate conversion coatings are used on aluminium alloys, primarily for their renowned corrosion resistant properties. Although these coatings are in common industrial use, neither the protection mechanisms, nor the coating interation with the intermetallic precipitation phases are fully understood. Macroscopic models have been developed in order to represent the galvanic cells present in aluminium alloys due to the presence of such intermetallic particles. Particles modelled include CuAl₂, FeAl₃ and Cu₂FeAl₇, all know to be cathodic to the aluminium matrix. Variations in deposition, both in composition and thickness, are indicative of the mechanisms of deposition over each phase. Characterisation of the coating deposition was carried out using X-ray photoelectron spectroscopy, Rutherford backscattering spectroscopy, Auger electron spectroscopy, scanning electron microscopy with X-ray analysis. Depositional characteristics have been determined for each phase. The coating on the intermetallic phases is primarily Al oxide, and is significantly thinner than the coating on the matrix. This coating on the matrix consists mainly of a mixed Cr/Al oxide. The coating on the intermetallic phases was only one tenth the thickness of the matrix coating, and contained higher levels of Fe, Al and O. Matrix coating chemistry predominated with Cr, O, Fe and N, indicative of a chromate conversion coating. The mechanism for reduced rates of deposition over intermetallic phases was found to be affected by fluorine ion attack leading to intermetallic de-alloying and decomposition of Fe(CN)₆²⁻ accelerator into amide groups on the matrix.