S. Peredkov

Magnetron-based source of neutral metal vapors for photoelectron spectroscopy

The construction of a magnetron-based source for neutral metal vapors is presented. The first photoelectron spectroscopy experiments with the source using synchrotron radiation at MAX-lab, Sweden are described. Photoelectron spectra of atomic copper, silver, and nickel are reported with an 80 meV resolution for Cu and Ag, previously not achieved in experiments using synchrotron light. (c) 2006 American Institute of Physics.

Synchrotron radiation parameters registration using beam cross-section image detector: The first experiments

Abstract Possibilities of non-destructive recording of synchrotron radiation (SR) beam parameters using Beam Cross-section Image Detector (BCID), which was designed before for the diagnostic of charged beams, have been estimated. The basic principles of the work of this detector are described. A developed detector for visualization of synchrotron radiation beam cross-section image is described briefly. The first tests of this detector were provided on SR beam at LURE (Orsay). Some of the results of these tests are described and discussed. The results obtained show the possibility of the use of ionization crossection detector for a prompt beam cross-section observation. Computer data processing of beam cross-section TV image make it possible to obtain size, position and shift of gravity centre of the SR beam, angle of beam downfall on the target continuously.

X-ray parabolic lenses made from glassy carbon by means of laser

Parabolic planar compound refractive lenses (CRLs) made from glassy carbon by means of laser ablation are presented. They have radii of curvatures of 5 and 200μm and geometric apertures of 40 and 900μm, respectively. The numbers of biconcave elements in the CRLs were 4, 7, and 200. The planar lenses allow formation of a linear focus of length comparable with the depths of their profiles. Usage of two CRLs in a crossed geometry provides formation of two-dimensional focus. The lenses were tested at the European Synchrotron Radiation Facility at the bending magnet beam line BM-5. The minimum experimental size of the focus has been achieved as 1.4μm.

A Deep X-ray Lithography beamline at the Kurchatov Synchrotron Radiation Source: First results

Abstract A Deep X-ray Lithography (DXRL) beamline at the Kurchatov Synchrotron Radiation Source (KSRS) has been constructed and commissioned. For the irradiation a simple exposure apparatus and synchrotron radiation with a critical energy of about 7 keV was used. Samples with resist thickness of 300 μm and 500 μm have been exposed using a test mask. SEM results are shown.

Spectrometer with vertical dispersion mode for studying chemical shifts in X-ray emission lines with the use of synchrotron radiation: preliminary experiment

The spectrometer proposed uses white synchrotron radiation for fluorescence excitation. The fluorescence analysis is carried out by a double crystal diffractometer in the vertical dispersion mode. We simulate experimental data taking the uranium Lα1 emission line (e = 13.6 keV, Δe = 11.3 eV) and Kurchatov Synchrotron Radiation Source parameters. We take into account the following parameters: the partial absorption cross section of the element under investigation μpart(e), the SR spectral distribution, the Gaussian vertical photon angle distribution σz′ph(e), and the Gaussian vertical electron linear and angle distributions σzel and σz′el. The emission X-ray line has been taken to have a Lorentz form. The transmission coefficient of the double crystal spectrometer in high dispersion position has been taken to have a Gauss-form σDar. The following results have been achieved. A measurement accuracy Δee ≅ 10−6 can be achieved when measuring for ∼ 100 s with E = 2.5 GeV and I = 100 mA. Here Δe is the statistic uncertainty of the line position and ϵ is the emission line energy. The natural line width will not be increased by the spectrometer convolutions by more than 20%, so the line form can be investigated very carefully. Based on piezoelectric transducers, the diffractometer is now being commissioned. A preliminary experiment in vertical dispersion mode has been performed and fitted with the theory.

Structural investigation of supported Cun clusters under vacuum and ambient air conditions using EXAFS spectroscopy

Extended X-ray absorption fine structure (EXAFS) measurements have been carried out to explore the size-dependent structure of deposited Cun clusters using the element-specific Kα fluorescence signal of copper. In particular, Cu55 and Cu35 have been deposited on a thin natural silica layer of a Si(100) wafer and have been investigated under both ultra-high vacuum and ambient air conditions. Pieces of evidence of an icosahedral structure of Cu55 and a densely-packed compact fcc-like geometry of Cu35 are concluded from a comparison of the magnitude EXAFS spectra and FEFF simulations of the geometry of the corresponding free clusters. The exceedingly small radial distances as revealed from the radial distribution plots of the pristine clusters can be explained by a severe increase (∼100%) in the scattering phase shift with respect to that of copper bulk. After exposure to ambient atmosphere, the EXAFS signal of “magic” Cu55 as well as that of Cu35 exhibits oxidation of the clusters showing a nearest-neighbour radial distance peak which agrees with the Cu–O bond length in amorphous copper hydroxide.