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An x-ray photoelectron spectroscopic (XPS) study of a thin film of S2N2 at −100 °C, involving the valence band, core-level and core-level shakeup, and energy-loss spectra, is reported. The results are analyzed in terms of a molecular orbital model and previous optical data. In addition, the thermally induced solid state polymerization of S2N2 to metallic (SN)x was studied by recording the XPS spectra at −40, 0, and 20 °C. The valence band data show changes of the highest filled molecular orbitals of S2N2, consistent with the process of polymerization to the metallic state.

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The Bureau International des Poids et Mesures has initiated world-wide intercomparisons of pressure standards. The intercomparison in the regime of very low pressures, i.e. 10-4 to 1 Pa, using Ar as the test gas, has now been completed with the participation of laboratories in nine countries (in alphabetical order): Czechoslovakia, Federal Republic of Germany, France, India, Italy, Japan, People's Republic of China, UK and United States of America. In addition, five of these laboratories made measurements using H2 as the test gas. Four spinning-rotor gauges were employed as transfer standards. The achieved transfer uncertainty between the pilot laboratory (Physikalisch-Technische Bundesanstalt) and a participating laboratory lies between 0.16% and 0.30% (1σ) for Ar and has allowed an intercomparison at this level of accuracy. At all investigated pressures the standards in the various laboratories lie within an interval of ±3% around the standard of the pilot laboratory. For a brief synopsis of the intercomparison results, the calibration data of each laboratory for one gas species are reduced to a single number, i.e., the average over the pressure range 10-3 to 1 Pa, although this procedure is somewhat arbitrary and obscures scatter and pressure-dependence of some calibration results. These averages deviate from their mean by not more than about 1%. Systematic deviations between some laboratories are clearly identifiable: however, for most of the laboratories it appears that these are compatible with the estimated uncertainties of the pressure generation and the transfer uncertainty.

The x-ray-photoelectron spectrum of powdered diamond samples in the binding-energy range -15 to 1050 eV is reported. The major features of the spectrum are the C 1g and surface contaminant 01s peaks, the carbon and oxygen Auger transitions, and diamond's valence-region structure. Plasma-resonance excitations are identified in the inelastic tail of the C ls peak. The valence-region spectrum is analyzed and corrected for the presence of what is interpreted to be extrinsic structure. The corrected spectrum maps out primarily the s-like states in. diamond's density of states, and indicates a valence-band width of 21eV.