Dynamical effects in the vibrationally resolved C 2s-1 photoionization cross section ratios of Methane

The vibrationally resolved C 2s photoionization cross-section of methane was investigated both theoretically and experimentally. When compared to that of C 1s photoionization, a rather different pattern has been observed, suggesting a strong interplay between the electron diffraction and interference effects

Vibration dependent branching and photoelectron angular distributions observed across the Cooper minimum region of bromobenzene

Vibrational state-resolved photoelectron anisotropy parameters, beta, for the ~X 2B1, ~B 2B2, and ~C2B1 state ionizations of bromobenzene have been recorded at photon energies ranging from 20.5 to 94 eV, so spanning the region of the expected bromine Cooper minimum (CM). The ~X state displays no CM and its beta value is also independent of vibrational level, in accord with the Franck-Condon Approximation. The ~B and ~ C state beta values display the CM to differing degrees, but both show a vibrational dependence that extends well below the obvious CM dip. Calculations are presented that replicate these observations of Franck-Condon Approximation breakdown spanning an extended photon energy range. This is the first demonstration of such wide-ranging breakdown detected in the beta anisotropy parameter in the absence of any resonance. Measured and calculated vibrational branching ratios for these states are also presented. Although the ~B state branching ratios remain constant, in accord with Franck-Condon expectations, the ~X and (especially) the ~C state ratios display weak, quasi-linear variations across the studied range of photon energy, but with no apparent correlation with the CM position

Dirac Spinor Waves and Solitons in Anisotropic Taub-NUT Spaces

We apply a new general method of anholonomic frames with associated nonlinear connection structure to construct new classes of exact solutions of Einstein-Dirac equations in five dimensional (5D)gravity. Such solutions are parametrized by off-diagonal metrics in coordinate (holonomic) bases, or, equivalently, by diagonal metrics given with respect to some anholonomic frames (pentads, or funfbiends, satisfing corresponding constraint relations). We consider two possibilities of generalization of the Taub NUT metric in order to obtain vacuum solutions of 5D Einsitein equations with effective renormalization of constants having distinguished anisotropies on an angular parameter or on extra dimension coordinate. The constructions are extended to solutions describing self-consistent propagations of 3D Dirac wave packets in 5D anisotropic Taub NUT spacetimes. We show that such anisotropic configurations of spinor matter can induce gravitational 3D solitons being solutions of Kadomtsev-Petviashvili or of sine-Gordon equations.Comment: revtex, 16 pages, version 4, affiliation changed, accepted to CQ

X-ray induced fragmentation of size-selected salt cluster-ions stored in an ion trap

Peer reviewe

The antibacterial activity and synergies between morusin and some antibiotics against MRSA strains – preliminary study

Mulberry (Morus alba L., Moraceae) is one of the most valuable and rich in phytochemicals plant. Morusin is a prenylated flavonoid present in mulberry roots and leaves. The in vitro antibacterial activity of morusin and its interactions with conventional antibiotics (oxacillin, amoxicillin and gentamicin) were evaluated against four methicillin resistant Staphylococcus aureus clinical isolates (MRSA T1 – T4) with resistance to oxacillin and cefoxitin which had been isolated from dogs with various pathologies. Minimum inhibitory concentrations (MICs) were determined by the microdilution method. The interactions were assessed by the chequerboard method - with interpretation through fractional inhibitory concentration index (FICI) and isobologram analysis. The interactions were confirmed by the time-kill assay. MICs varied between 3.125 and 6.25μg/mL for morusin alone against all four MRSA clinical isolates. Chequerboard method showed synergies for the combinations: morusin – oxacillin (FICI=0.024 - 0.27), morusin – amoxicillin (FICI=0.024 - 0.27) and morusin - gentamicin (FICI=0.05 - 0.12) against all four tested isolates. Time-kill assay determined synergies for the following combinations: morusin – oxacillin against MRSA T1, morusin – amoxicillin against MRSA T2 and morusin - gentamicin against all four isolates. Our preliminary study evaluated the antibacterial activity of morusin and its ability to act synergistically with antibiotics; these results suggest that morusin might be a promising strategy to overcome antibiotic resistence

Vibrationally resolved B 1s photoionization cross section of BF3

We present a study of the vibrationally resolved B 1s photoionization cross section of the BF 3 molecule. A combination of high-resolution photoelectron spectroscopy measurements and of state-of-the-art calculations shows the evolution of the photon energy dependence of the cross section from a complete trapping of the photoelectron wave (low energies) to oscillations due to intramolecular scattering. These diffraction patterns allow to access structural information of both the neutral molecule and the core -hole species generated upon photoabsoptio

Characterizing crystalline defects in single nanoparticles from angular correlations of single-shot diffracted X-rays

Characterizing and controlling the uniformity of nanoparticles is crucial for their application in science and technology because crystalline defects in the nanoparticles strongly affect their unique properties. Recently, ultra-short and ultra-bright X-ray pulses provided by X-ray free-electron lasers (XFELs) opened up the possibility of structure determination of nanometre-scale matter with angstrom spatial resolution. However, it is often difficult to reconstruct the 3D structural information from single-shot X-ray diffraction patterns owing to the random orientation of the particles. This report proposes an analysis approach for characterizing defects in nanoparticles using wide-angle X-ray scattering (WAXS) data from free-flying single nanoparticles. The analysis method is based on the concept of correlated X-ray scattering, in which correlations of scattered X-ray are used to recover detailed structural information. WAXS experiments of xenon nanoparticles, or clusters, were conducted at an XFEL facility in Japan by using the SPring-8 Angstrom compact free-electron laser (SACLA). Bragg spots in the recorded single-shot X-ray diffraction patterns showed clear angular correlations, which offered significant structural information on the nanoparticles. The experimental angular correlations were reproduced by numerical simulation in which kinematical theory of diffraction was combined with geometric calculations. We also explain the diffuse scattering intensity as being due to the stacking faults in the xenon clusters

Following the Birth of a Nanoplasma Produced by an Ultrashort Hard-X-Ray Laser in Xenon Clusters

X-ray free-electron lasers (XFELs) made available a new regime of x-ray intensities, revolutionizing the ultrafast structure determination and laying the foundations of the novel field of nonlinear x-ray optics. Although earlier studies revealed nanoplasma formation when an XFEL pulse interacts with any nanometer-scale matter, the formation process itself has never been decrypted and its timescale was unknown. Here we show that time-resolved ion yield measurements combined with a near-infrared laser probe reveal a surprisingly ultrafast population (similar to 12 fs), followed by a slower depopulation (similar to 250 fs) of highly excited states of atomic fragments generated in the process of XFEL-induced nanoplasma formation. Inelastic scattering of Auger electrons and interatomic Coulombic decay are suggested as the mechanisms populating and depopulating, respectively, these excited states. The observed response occurs within the typical x-ray pulse durations and affects x-ray scattering, thus providing key information on the foundations of x-ray imaging with XFELs

Real-time observation of X-ray-induced intramolecular and interatomic electronic decay in CH2I2

The increasing availability of X-ray free-electron lasers (XFELs) has catalyzed the development of single-object structural determination and of structural dynamics tracking in realtime. Disentangling the molecular-level reactions triggered by the interaction with an XFEL pulse is a fundamental step towards developing such applications. Here we report real-time observations of XFEL-induced electronic decay via short-lived transient electronic states in the diiodomethane molecule, using a femtosecond near-infrared probe laser. We determine the lifetimes of the transient states populated during the XFEL-induced Auger cascades and find that multiply charged iodine ions are issued from short-lived (similar to 20 fs) transient states, whereas the singly charged ones originate from significantly longer-lived states (similar to 100 fs). We identify the mechanisms behind these different time scales: contrary to the short-lived transient states which relax by molecular Auger decay, the long-lived ones decay by an interatomic Coulombic decay between two iodine atoms, during the molecular fragmentation