Nonlinear dispersion in resonant Auger decay of H₂O molecules

We have measured the resonant Auger decay spectrum of the water molecule at the oxygen K edge. Strong deviations from the expected linear dispersion of the participator lines (which correspond to single-hole valence states) are observed. In a simplified picture the effect can be attributed to the combined effect of the intermediate- and final-state potential curves

Subnatural Linewidths in Core Level Excitation Spectra

We have measured a core excitation spectrum on the N2 1s→π* transition in which the experimental linewidth is limited by the instrumental resolution rather than by the lifetime of the core hole. The measurement is performed by recording the partial yield of resonant Auger electrons within a fixed kinetic energy window. The factors contributing to the line shape and the general applicability of the method are discussed

Photofragmentation of SiF4 upon Si 2p and F 1s Core Excitation: Cation and Anion Yield Spectroscopy

We have studied the fragmentation dynamics of core-excited SiF4 by means of soft-x-ray photoexcitation and partial positive and negative ion yield measurements around the Si L2,3-shell and F K-shell ionization thresholds. All detectable ionic fragments are reported and we observe significant differences between the various partial ion yields near the Si 2p threshold. The differences are similar to our previous results from CH3Cl showing more extended fragmentation in correspondence to transitions to Rydberg states. At variance with smaller systems, we observe negative ion production in the shape resonance region. This can be related to the possibility in a relatively large system to dissipate positive charge over several channels

Variation of Cross-Section Enhancement in Decay Spectra of CO under Resonant Raman Conditions

We have measured participator and spectator decay at several photon energies within the range of the lifetime-broadened first vibrational component of the C 1s→π* resonance in CO. From the branching ratios it is evident that the resonant enhancement is different for single-hole and two-hole–one-electron states: The maximum in the resonant intensity peaks at different photon energies. It now becomes necessary to calculate energy-dependent transition matrix elements within the lifetime-broadening range

Influence of multielectron excitations on the O 1s photoionization in CO₂

High-resolution O 1s photoelectron spectra of the CO2 molecule have been measured in the region of the resonant features above the O K edge. The cross sections and asymmetry parameters were determined for the vibrational components of the O 1s photoelectron line. The vibrational fine structure is completely dominated by the antisymmetric stretching mode, which arises due to vibronic coupling. The O 1s line is accompanied by a rich satellite structure. Auger electron spectra have been measured at the energies of the continuum resonances and used as an indirect probe for multielectron excitations. The shoulder on the low-energy side of the 4σu shape resonance is due to double excitations that decay via spectator processes

Anion and Cation-yield Spectroscopy of Core-excited SF6

We report an extensive study on total and partial-ion-yield spectroscopy around both the S 2p and F 1s thresholds in SF6. All positive and negative single-ion channels have been measured. Below the F 1s threshold we detect a large variation in relative intensity of the resonant structures according to the specific channel monitored, indicating selective fragmentation. Above threshold, at variance with previous cases described by us, we detect high-intensity structures related to shape resonances not only in the cation channels but also for the anions. We discuss the applicability and limits of a model we have developed for the analysis of shape resonances in anion yields as a function of molecular size

Humoral and cellular response to BoHV-1 in buffalo and cattle treated with an inactivated marker vaccine

The study is aimed at assessing and comparing the immune response to BoHV-1 elicited by an inactivated marker vaccine in buffaloes and cattle. Vaccination did not produced any local or general reactions in buffaloes. Seroneutralizing antibodies and cellular response by IFN-γ- test have been detected in buffaloes and cattle after a prime/ booster vaccination strategy. Humoral and cellular responses were significantly higher in cattle than in buffaloes. Data pointed out the possibility to use the marker vaccine in buffaloes. However, further studies must be planned to assess the immune pressure of marker vaccines in terms of IBR eradicative attitude in infected buffalo herds