X-ray photoelectron spectra of uranium and uranium oxides. Correlation with the half-life of 235Um.

Uranium metal and the uranium oxides UO₂, U₃O₈, UO₃ are studied by photoelectron spectroscopy. Chemical shifts of the 4f electronic cor     

Work function measurements with a high resolution electron energy loss spectrometer: Application to the interaction of oxygen with Ag(110)

The monochromatized electron beam of a high resolution electron energy loss (HREEL) spectrometer is used for accurate (±5 meV) measurement of the work function changes during exposure of a Ag(110) single crystal surface to oxygen. Absolute calibration of the results is made by comparison with Kelvin probe data. The procedure allows the precise determination of the electron impact energy, which is an important parameter for quantitative HREELS analysis. Furthermore, in the case of oxygen adsorbed on Ag(110), the occurrence of several LEED (n×1) superstructures enables a calibration of the HREELS data with respect to surface coverage.     

HREELS study of formic acid adsorption on gold (110) and (111) surfaces.

The adsorption at 100 K and the temperature decomposition of formic acid were investigated on (110) and (111) gold single crystal surfaces by high resolution electron energy loss spectroscopy. A multilayer build-up of physisorbed HCOOH with intense hydrogen bondings was observed at increasing coverages for the two gold surface orientations. Above room temperature, formic acid decomposed and desorbed from the (110) crystal, whereas it evolved into an intermediate formic anhydride on the (111) face. Further heating produced on the surfaces species similar to those observed on oxygen treated metals.     

Z4-Kerdock Codes, Orthogonal Spreads, and Extremal Euclidean Line-Sets

When m is odd, spreads in an orthogonal vector space of type⁺(2m + 2,2) are related to binary Kerdock codes and extremalline-sets in 2^{m + 1} with prescribed angles. Spreads in a 2m-dimensionalbinary symplectic vector space are related to Kerdock codesover Z₄ and extremal line-sets in with prescribed angles. These connections involve binary, realand complex geometry associated with extraspecial 2-groups.A geometric map from symplectic to orthogonal spreads is shownto induce the Gray map from a corresponding Z₄-Kerdock codeto its binary image. These geometric considerations lead tothe construction, for any odd composite m, of large numbersof Z₄-Kerdock codes. They also produce new Z₄-linear Kerdockand Preparata codes. 1991 Mathematics Subject Classification:primary 94B60; secondary 51M15, 20C99.