A new compact soft x ray spectrometer for resonant inelastic x ray scattering studies at PETRA III

We present a newly designed compact grating spectrometer for the energy range from 210 eV to 1250 eV, which would include the K amp; 945;1,2 emission lines of vital elements like C, N, and O. The spectrometer is based on a grazing incidence spherical varied line spacing grating with 2400 l mm at its center and a radius of curvature of 58 542 mm. First, results show a resolving power of around 1000 at an energy of 550 eV and a working spectrometer for high vacuum 10 amp; 8722;4 mbar environment without losing photon intensit

Correlation-Driven Transient Hole Dynamics Resolved in Space and Time in the Isopropanol Molecule

The possibility of suddenly ionized molecules undergoing extremely fast electron hole (or hole) dynamics prior to significant structural change was first recognized more than 20 years ago and termed charge migration. The accurate probing of ultrafast electron hole dynamics requires measurements that have both sufficient temporal resolution and can detect the localization of a specific hole within the molecule. We report an investigation of the dynamics of inner valence hole states in isopropanol where we use an x-ray pump–x-ray probe experiment, with site and state-specific probing of a transient hole state localized near the oxygen atom in the molecule, together with an ab initio theoretical treatment. We record the signature of transient hole dynamics and make the first tentative observation of dynamics driven by frustrated Auger-Meitner transitions. We verify that the effective hole lifetime is consistent with our theoretical prediction. This state-specific measurement paves the way to widespread application for observations of transient hole dynamics localized in space and time in molecules and thus to charge transfer phenomena that are fundamental in chemical and material physics

Oxygen K-edge x-ray-emission-threshold-electron coincidence spectrum of CO2

The oxygen K-edge x-ray-emission–threshold-electron coincidence spectrum of CO2 is presented. A twostep model, describing the result as a threshold-photoelectron spectrum free from post-collision interaction effects, predicts the salient features of the measured spectrum. Small discrepancies from the predictions are discussed in terms of threshold ionization dynamics

X-ray-emission-threshold-electron coincidence spectroscopy

Using a penetration-field threshold photoelectron (TPE) analyzer and efficient photon detectors X-ray-emission-threshold-electron coincidence (XETECO) spectroscopy has been developed to a point where peak shape analysis becomes meaningful. The spectra can, on the present level of accuracy, be interpreted as conventional TPE spectra free from post collision interaction effects. For the neon atom and the nitrogen molecule we find a detailed correspondence with state-of-the-art photoemission spectra, both regarding peak positions, line shapes, and relative intensities. Intensity redistribution due to fast core vacancy rearrangement processes in systems with close-lying core levels, like O-2, N2O, and NO is briefly discussed. It is demonstrated that even the complex threshold behavior at the F K threshold in SF6 leads to a well-defined XETECO peak, directly corresponding to classical photoemission results. (C) 2004 Elsevier B.V. All rights reserved

Radiative and relativistic effects in the decay of highly-excited states in helium

A recent experimental study [J.-E. Rubensson et al., Phys. Rev. Lett. 83, 947 (1999)] measured a significant fluorescence yield of the He(2lnl0) photoexcited resonances, showing major qualitative differences from nonrelativistic predictions. We present a further theoretical study of these states, and perform R-matrix multichannel quantum defect theory calculations to extract fluorescence and ionization cross sections. These theoretical results are in excellent agreement with newer, higher-resolution measurements. Radiative and spin-orbit effects are quantified and shown to play an important role in the overall characterization of highly excited states

The electronic structure of perfluorodecalin studied by soft X ray spectroscopy and electronic structure calculations

Fluorine and carbon K absorption and emission spectra of liquid perfluorodecalin are presented and analyzed in terms of density functional calculations configuration interaction. A comprehensive view of the electronic structure is given, and site specific intramolecular interactions are investigated in detail. It is found that, while the outer fluorine atoms have excess charge in the ground state, the lowest excitations must be associated with charge transfer towards the inner carbon atom

Core level ionization dynamics in small molecules studied by x-ray-emission threshold-electron coincidence spectroscopy

X-ray-emission threshold-electron coincidence spectroscopy has been applied to N2, O2, and N2O. The main features of the spectra can be interpreted as conventional core level threshold electron spectra, free from postcollision interaction effects. The relative cross sections for adiabatic ionization of close-lying core hole states and vibrational substates are presented. The results are compared to theoretical predictions and state-ofthe- art photoelectron spectra and are discussed in terms of direct threshold ionization and core vacancy rearrangement processes

Stationary and dispersive features in resonant inelastic soft X-ray scattering at the Ge 3p resonances

Resonant inelastic soft X-ray scattering at the 3p resonances in crystalline Ge is presented. Both stationary and dispersive features are observed in a wide energy range above as well as below the ionization limits. These observations are in agreement with theoretical predictions based on a two-step model where the initially excited electron has no influence on the emission step. Excess population of states in the conduction band is found, and discussed in terms of attosecond electron dynamics. (c) 2009 Elsevier B.V. All rights reserved

Stationary and dispersive features in resonant inelastic soft X-ray scattering at the Ge 3p resonances

Resonant inelastic soft X-ray scattering at the 3p resonances in crystalline Ge is presented. Both stationary and dispersive features are observed in a wide energy range above as well as below the ionization limits. These observations are in agreement with theoretical predictions based on a two-step model where the initially excited electron has no influence on the emission step. Excess population of states in the conduction band is found, and discussed in terms of attosecond electron dynamics. (c) 2009 Elsevier B.V. All rights reserved

Stationary and dispersive features in resonant inelastic soft X-ray scattering at the Ge 3p resonances

Resonant inelastic soft X-ray scattering at the 3p resonances in crystalline Ge is presented. Both stationary and dispersive features are observed in a wide energy range above as well as below the ionization limits. These observations are in agreement with theoretical predictions based on a two-step model where the initially excited electron has no influence on the emission step. Excess population of states in the conduction band is found, and discussed in terms of attosecond electron dynamics