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cited By 7; International audience; Valence band states of GeXAs40-XS60 glasses and amorphous films are obtained by means of X-ray photoelectron spectroscopy. Differences between the broad bands in the spectra, connected with differences in the composition as well as with structural changes initiated by illumination and/or annealing arc identified and discussed.

International audience; Several WOySz tungsten oxysulphide thin films were tested as positive electrodes for lithium microbatteries. The amorphous WO1×05S2 thin film was found very promising. A capacity decrease occurred during the first few cycles, after which the films were able to intercalate reversibly up to 1×1 lithium ion per formula unit under high regime (75 mA/cm2)...

International audience; Ethenylphosphine and prop-1-en-2-ylphosphine, obtained by flash-vacuum thermolysis of the corresponding Diels-Alder adducts, have been characterized by their photoelectron spectra. In both cases, the broad shape of the first two bands respectively at 9.65 and 10.85 eV for ethenylphosphine and at 9.50 and 10.3 eV for prop-1-en-2-ylphosphine can only be accounted for if we assume a free-rotating P-C bond. This conclusion was inferred from a complete theoretical study of the rotation process of the PH2 group around the P-C bond. Two privileged forms were found: a syn form (φ = 0, the lone pair of the phosphorus eclipsing the P-C bond) and a gauche form 3.5 kJ·mol-1 less stable (φ = 127°), separated by low rotation barriers (8.19 and 10.74 kJ·mol-1). Evaluation of the accurate ionization potentials according to a configuration interaction formalism has been achieved for ethenylphosphine in different conformations. The results of these calculations clearly indicate that during the rotation process the energy of the first two ionic states extends over a 0.4 eV interval. © 1988 American Chemical Society.

International audience; Phosphaethene, the unstable parent compound in the phosphaalkenes series, has been thoroughly investigated using theoretical calculations. For the first time, its electronic structure is evidenced from its photoelectron spectrum. The PE spectra of phosphaethene and 1-phosphapropene, generated in the gas phase by the respective vacuum dehydrochlorination of chloromethylphosphine and 1-chloroethylphosphine, have been recorded in situ by the use of a vacuum device directly coupled to the spectrophotometer. The vertical πP=C and np ionization energies are observed respectively at 10.30 and 10.70 eV for phosphaethene and at 9.75 and 10.35 eV for 1-phosphapropene. The band's characterizations are discussed through correlations with the corresponding imines and with substituted phosphaalkenes and are confirmed by ab initio theoretical calculations. The results indicate a rather significant energetic separation between the two first πP=C and np ionic states. © 1988 American Chemical Society.