We develop a microscopic model for the interaction of small rare gas clusters with soft X-ray radiation. It is shown that, while the overall charging of the clusters is rather low, unexpectedly high atomic charge states can arise due to charge imbalances inside the cluster. The mechanism does not require unusually high absorption rates, and the heating can be described by standard inverse brems...

We report experimental evidence for the charge-orbital ordering in magnetite below the Verwey transition temperature T(V). Measurements of O K-edge resonant x-ray scattering on magnetite reveal that the O 2p states in the vicinity of the Fermi level exhibit a charge-orbital ordering along the c axis with a spatial periodicity of the doubled lattice parameter of the undistorted cubic phase. Such...

Local antiferromagnetism coexists with superconductivity in the cuprates. Charge segregation provides a way to reconcile these properties. Direct evidence for modulated spin and charge densities has been found in neutron and X-ray scattering studies of Nd-doped La2−xSrxCuO4. Here we discuss the nature of the modulation, and present some new results for a Zn-doped sample. Some of the open questi...

A collimated Au source was used to determine the charge collection efficiency (CCE) at several locations along the length of a 3.4 x 3.4 x 5.5 mm CdZnTe bar detector both in planar configuration and with Frisch collars of varying length. For each configuration, a 0.50 mm long region spanning the width of the device was irradiated with 411 keV gamma rays produced by a neutron activated gold foil...

When the electron density in a crystal or a quasicrystal is reconstructed from its Fourier modes, the global minimum value of the density is sensitively dependent on the relative phases of the modes. The set of phases that maximizes the value of the global minimum corresponds, by positivity of the density, to the density having the minimum total charge that is consistent with the measured Fouri...

Calibration procedures are described for use with electronic x-ray detectors, with an emphasis on detectors based on fiber-optically coupled charge-coupled devices. Methods are detailed for removing spurious events, pixel pedestals, dark-current, spatial distortion, and intensity response variations for both small-angle and wide-angle applications. The accuracy of the calibration procedures is ...

The crystal structure of Fe(3)O(4) below the 122 K Verwey transition has been refined using high-resolution x-ray and neutron powder diffraction data. The refinements give direct evidence for charge ordering (CO) over four independent octahedral Fe sites, two with a charge of +2.4 and the other two of +2.6. CO schemes consistent with our model do not meet the widely accepted Anderson condition ...

We have observed large second-order nonlinear optical and vibrational circular dichroism (VCD) responses in a charge-transfer-type L-Histidinium salt. Using X-ray Diffraction, VCD spectroscopy, and time-dependent density functional theory to characterize the compound, we employ a two-level model to explain and quantify the strongly enhanced optical signals. We find that both linear and nonlinea...

X-ray irradiation usually induces disorders in a crystal, for example, displacement of the atomic position. In the case of molecular materials, the irradiation produces the molecular defects, which are radiolysed by ionizing radiation. This kind of molecular defect permanently remains, while the irradiation damage in inorganic materials in general is only due to atomic displacements which can b...

The ionization and charge separation processes of nanoplasmas created by resonant excitation of atomic clusters in intense soft x-ray pulses have been investigated. Through irradiation with femtosecond pulses from the FLASH free electron laser (FEL) at λ = 13.7 nm and power densities exceeding 1014 W cm−2 the clusters are highly ionized with transient atomic charge states up to 9+. Variation of...