Sur les conditions de petite simplification qui permettent d'utiliser l'algorithme de Dehn

Sans résumé     

The infrared spectrum of californium-249

The Cf-249 spectrum between 3700 and 12,000 cm^?1 has been recorded. The strongest 90 lines are listed.     

Etude de la Fragmentation en Spectrographie de Masse de Spiropyrannes Benzodithioliques. Influence de la Position et de la Nature des Substituants

The mass spectra of 12 benzodithiolic spiropyrans are reported. Their fragmentation pathways have been determined by exact mass and metastable transition measurements. The nature of the fragmentation is strongly dependent upon the position and nature of the substituents. A comparison is made with their photo and thermochemical decompositions.     

Photoisomerization processes in the IR-140 laser dye

The photoisomerization processes in the well known IR-140 laser dye and in the closest relevant DTTC model have been investigated by a mode-locked laser spectroscopy in order to observe the influence of a partial rigidization of the polymethine chain. The kinetic, spectral and thermodynamic parameters have been measured; the correlations between the transient quantum yields and the laser efficiency under flash-lamped pumping are discussed. Evidence is given for a surprising solvent effect upon the photoisomerization process.     

Epitaxial relationships between Al,Ag and GaAs{001} surfaces

Detailed results concerning the orientation of Al and Ag layers grown by MBE onto GaAs{001} surfaces are reported. The observed crystallographic relationships have been found to depend only on the growth temperature in the case of Ag, while for Al the situation is more complex. Possible effects of other parameters such as structure and stoichiometry of the starting GaAs surface and growth rate, are discussed and compared with other results recently reported.     

Sur les propriétés électriques et magnétiques des phases MxZrS2 (M = Fe,Co, Ni)

The M_xZrS₂ systems with M = Fe, Co, Ni have been investigated: nonstoichiometric phases are observed with M in the tetrahedral sites between ZrS₂ layers. Electric measurements characterize a semiconducting behaviour and suggest the occurrence of trigonal zirconium + III clusters. Magnetic measurements seem to confirm also MM bond formation.     

Etude du chromatisme d'un systeme optique par photographie “speckle”

Speckle photography experiments have been used for studying optical systems and more recently we have used image speckle photography to measure displacements and deformations of a partial diffuser. The same method is now used for studying chromatic aberrations of a lens system. Experimental results are given for three optical lenses.