Diffraction dissociation at the CERN pulsedpp collider at c.m. Energies of 900 and 200 GeV

Cross-sections for diffractive particle production and pseudorapidity distributions of the decay products of diffractive states are presented. The data were obtained with the UA 5 streamer chamber detector at the CERNpp Collider operated in a new pulsed mode yieldingpp interactions at c.m. energies of 900 and 200 GeV. Data recorded with a special trigger designed to select a sample of events enriched in single-diffractive interactions clearly favour ap _t -limited fragmentation of diffractive states. The cross-section for single-diffractive particle production ? was found to be 7.8±0.5±1.1 mb at 900 GeV and 4.8±0.5±0.8 mb at 200 GeV (first error statistical, second systematic). From the pseudorapidity distribution of diffractive states we deduce the average number of charged particles to be 6.5±1.0 at 900 GeV and 4.1±1.1 at 200 GeV. Furthermore we report on our estimates for the cross-section of double-diffractive particle production at both Collider energies.     

Solid state effects in the IR spectrum of octahydridosilasesquioxane

Infrared spectrum of Octahydridosilasesquioxane, in the solid state, is reported and analyzed to show the presence of significant solid state effects. This is in marked contrast with the reported Raman spectroscopic studies of this compound in the solid state where no evidence for such a proliferation of these effects were found. It is found that the normal modes with radial motion of the atoms in their normal coordinate are distinguishable from other vibrations by the distinct correlations between the band intensity and the solid state splitting observed in the IR spectrum. This new insight suggests an interchange of the literature assignments of the two modes nu27 and nu29 in the IR spectrum and a different origin to the doublet of bands in the Raman spectrum at 883 and 897 cm(-1).     

Vibrational coupling in oxo-centred trinuclear clusters: oxygen-16/18 isotopic substitution studies of [Fe3III(O)(O2CC(CH3)3)6(py)3][FeCl4] and [Fe2(III)FeII(O)(O2CC(CH3)3)6(py)3

IR spectra are reported for the compounds [Fe3O(O2CC(CH3)3)6(py)3][FeCl4] and [Fe3O(O2CC(CH3)3)6(py)3]. Using isotopic substitution at the central oxygen atom, the assignments of the in-plane and out-of-plane vibrations of this atom are confirmed, and coupling is demonstrated between the in-plane modes v(as)(Fe3O) and carboxylate deformation modes rho(r)(C-CO2).