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[en] Full text: In this work we describe the present status, facilities and commissioning of the LNLS D05A beamline, based on a Toroidal Grating Monochromator (TGM) plus control and data acquisition electronics. The TGM beamline was the first one to come up in operation at LNLS. It provides vacuum ultraviolet photons with energies ranging from 12 to 310 eV, in the maximum photon flux region generated by the LNLS storage ring. The photon energy range is covered using three gratings interchangeable at high vacuum. The high flux ultraviolet monochromatic radiation provided by the TGM beamline at LNLS has being used to investigate the electronic structure of atoms and molecules, and also to examine the ways in which ionized molecules break up. The beamline is also a good source of circularly polarized light, a valuable property for dichroism experiments. Different experimental end stations can now be attached at the end of the beamline. Besides users own chambers, the users can make use of several LNLS facilities: a standard chamber, a rotatable station for photoelectron-photoion-photoion coincidence spectroscopy, two surface science stations and a laser cooling and trapping station with a time of fight spectrometer.(author)

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[en] The photo fragmentation of a core-excited halogenated compound, Halothane (C₂ F₃ Cl Br), generally used as anesthetic by inhalation, has been studied using high energy photons and electrons near C 1s ionization edge (∼300 eV), using time-of-flight mass spectrometry in multicoincidence mode. We observe strong differences between the molecular fragmentation induced by photons and electron impact. (author)

[en] Different lifetime broadenings in molecular-field-split 2p core levels in H₂S are predicted theoretically and are identified in an experimental investigation of the S 2p Auger electron spectrum. The measurements were performed for the transition to the vibrationally resolved X¹A₁ ground state of H₂S²⁺. The lifetimes of the 3e_1/2 and 5e_1/2 levels of the 2p ionized molecule are found to be 64 and 74 meV, respectively. This unambiguous determination of the lifetime difference of 10±1 meV is only possible as the 4e_1/2→X¹A₁(2b₁^-2) decay channel that overlaps the 5e_1/2→X¹A₁(2b₁^-2) channel is practically suppressed in Auger decay in H₂S. The lifetime difference is confirmed by ab initio calculations. A theoretical analysis shows that it results from the mutual orientation of the core hole in the intermediate states and the valence electron density in the sulfur 3p orbitals. Both are strongly influenced by the chemical bond. Thus the observed effect is the direct result of a fundamental property of molecular electronic structure

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