[en] The PS120 variant of Chinese hamster lung fibroblasts which lacks Na⁺/H⁺ exchange activity was used to investigate bicarbonate transport systems and their role in intracellular pH (pH/sub i/) regulation. When pH/sub i/ was decreased by acid load, bicarbonate caused pH/sub i/ increase and stimulated ³⁶Cl^- efflux from the cells, both in a Na⁺-dependent manner. These results together with previous findings that bicarbonate stimulates ²²Na⁺ uptake in PS120 cells demonstrate the presence of a Na⁺-linked Cl^-/HCO₃^- exchange system. In cells with normal initial pH/sub i/, bicarbonate caused Na⁺-independent pH/sub i/ increase in Cl^--free solutions and stimulated Na⁺-independent ³⁶Cl^- efflux, indicating that a Na⁺-independent Cl^-/HCO₃^- exchanger is also present in the cell. Na⁺-linked and Na⁺-independent Cl^-/HCO^3- exchange is apparently mediated by two distinct systems, since a [(tetrahydrofluorene-7-yl)oxy]acetic acid derivative selectively inhibits the Na⁺-independent exchanger. An additional distinctive features is a 10-fold lower affinity for chloride of the Na⁺-linked exchanger. The Na⁺-linked and Na⁺-independent Cl^-/HCO₃^- exchange systems are likely to protect the cell from acid and alkaline load, respectively

[en] For the element niobium, whose energy level structure was considered to be well known regarding the low-lying levels, the energy values of four low-lying levels, listed in Moore's tables of atomic energy levels, were found to be incorrect. The correct positions of these levels have been revealed, and, additionally, two new levels have been detected using laser-induced fluorescence spectroscopy in the wavelength region from 470 nm to 505 nm. (authors)

[en] The color X-ray camera (SLcam(R)) is a full-field single photon imager. As stand-alone camera, it is applicable for energy and space-resolved X-ray detection measurements. The exchangeable poly-capillary optics in front of a beryllium entrance window conducts X-ray photons from the probe to distinguished energy dispersive pixels on a pnCCD. The dedicated software enables the acquisition and the online processing of the spectral data for all 69696 pixels, leading to a real-time visualization of the element distribution in a sample. No scanning system is employed. A first elemental composition image of the sample is visible within minutes while statistics is improving in the course of time. Straight poly-capillary optics allows for 1:1 imaging with a space resolution of 50 μm and no limited depth of sharpness, ideal to map uneven objects. Using conically shaped optics, a magnification of 6 times was achieved with a space resolution of 10 μm. We present a measurement with a laboratory source showing the camera capability to perform fast full-field X-ray Fluorescence (FF-XRF) imaging with an easy, portable and modular setup.

[en] Full text: Photodetachment microscopy was performed on a beam of S^- generated by a hot cathode discharge in a mixture of 98 % Ar and 2 % CS₂, with the sulfur isotopes in natural abundances. Isotope 34 was selected by a Wien velocity filter. Laser excitation was provided by a CW ring laser operating with the Rhodamine 590 dye. The laser wavenumber was measured by an Angstroem WS-U lambda meter, with an accuracy better than 10^-3 cm^-1. Subtracting the photoelectron energy found by analyzing the electron interferogram from the photon energy, one can determine the electron affinity ^eA. The result for ^eA(³⁴S) is 16 752.978(10) cm^-1, to be compared to the previously measured ^eA(³²S)=16 752.976(4) cm^-1. Technical correlations between the two measurements lets the isotope shift Δ_exp = ^eA(³⁴S) - ^eA(³²S) be a little more accurate than the more imprecise electron affinity. Numerically Δ_exp = + 0.002(8) cm^-1, in which the (2σ) error bars leave room for a normal or anomalous result. Ab initio calculations of the isotope shift on the electron affinity from the infinite-mass systems S^-/S were carried out, adopting the multiconfiguration Hartree-Fock (MCHF) approach using the ATSP2K package. Our model includes in a systematic way valence correlation, limiting the core to the n=2 shell. The one-electron orbitals are optimized using single- and double- multi-reference expansions. Configuration-interaction (CI) calculations including up to 6 · 10⁵ configuration state functions were performed in order to complete the convergence patterns of the S^- energy, resulting in a unextrapolated nonrelativistic electron affinity of ^eA(^∞S) 16 987(44)cm^-1. The theoretical isotope shift value Δ_theor = ^eA(³⁴S) - ^eA(³²S) = -0.0022(2)cm^-1 is found to be rather small but definitely negative. The analysis of the various contributions reveals a very large specific mass shift that counterbalances the normal mass shift, while the positive field shift is smaller than the total mass contribution by one order of magnitude. (author)

[en] Highlights: • Description of compact angle-resolved X-ray fluorescence spectrometer. • Exploiting scanning-free grazing emission X-ray fluorescence approach. • Energy dispersive charge-coupled device with single-photon detection. • Enabling non-destructive, quantitative elemental depth profiling. • Depth profiling of nano-structured stratified specimen, here CIGS solar cells. An angle resolved X-ray fluorescence spectrometer based on the concept of scanning-free shallow detection with energy-dispersive area detectors is presented. The instrument is characterized with respect to energy resolution, linearity, angular discrimination and repeatability and the necessary data evaluation strategies are presented in detail. As demonstration of its capabilities and showcase for potential applications, two different copper indium gallium (di)selenide (CIGS) absorber layers, typically applied in thin film solar cells, are analyzed. In combination with quantitative (but integral) results for layer composition and layer thickness from a commercial XRF spectrometer, depth profiles of the Ga concentration of both ≈ 2 μm thin samples are obtained. The results of the novel spectrometer compare well with quantitative depth-profiles obtained from glow-discharge optical emission spectrometry. The combination of simplicity, stability and efficiency of the spectrometer concept makes it a potential candidate for industrial applications. Description of compact angle-resolved X-ray fluorescence spectrometer. Exploiting scanning-free grazing emission X-ray fluorescence approach. Energy dispersive charge-coupled device with single-photon detection. Enabling non-destructive, quantitative elemental depth profiling. Depth profiling of nano-structured stratified specimen, here CIGS solar cells.

[en] To facilitate the treatment of the expressions from the theory of angular momentum and the atomic shell model, we have developed the RACAH program during the past years. Today it is the most developed tool for symbolic manipulation of expressions in atomic physics. The RACAH program is not only able to provide the standard quantities from the atomic shell theory, but it also supports the symbolic manipulations and the numerical computations of the expressions from the angular momentum theory. The latest progress in extending the program for complex atoms with several open shells is reported and its application for newly developed expressions of the hyperfine structure is demonstrated

[en] This paper lays down the theoretical bases and the methods used in the Fast Optimal Retrievals on Layers for IASI (FORLI) software, which is developed and maintained at the “Université Libre de Bruxelles” (ULB) with the support of the “Laboratoire Atmosphères, Milieux, Observations Spatiales” (LATMOS) to process radiance spectra from the Infrared Atmospheric Sounding Interferometer (IASI) in the perspective of local to global chemistry applications. The forward radiative transfer model (RTM) and the retrieval approaches are formulated and numerical approximations are described. The aim of FORLI is near-real-time provision of global scale concentrations of trace gases from IASI, either integrated over the altitude range of the atmosphere (total columns) or vertically resolved. To this end, FORLI uses precalculated table of absorbances. At the time of writing three gas-specific versions of this algorithm have been set up: FORLI-CO, FORLI-O₃ and FORLI-HNO₃. The performances of each are reviewed and illustrations of results and early validations are provided, making the link to recent scientific publications. In this paper we stress the challenges raised by near-real-time processing of IASI, shortly describe the processing chain set up at ULB and draw perspectives for future developments and applications.

[en] The recently installed and unique PIXE (particle-induced X-ray emission) set-up at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) is mainly dedicated to applications for a detailed overview of elemental composition over large sample areas within a short time even at trace level. The so-called High-Speed-PIXE (HS-PIXE), a combination of a pnCCD-based pixel-detector with polycapillary X-ray optics, offers simultaneous imaging of sample areas up to 12 × 12 mm"2 with a lateral resolution better than 100 μm. Each of the 264 × 264 individual pixels detects X-ray photons in an energy range from 2 keV to 20 keV with an energy resolution of 152 eV (@Mn-K_α). A high precision sample manipulator offers the inspection of areas up to 250 × 250 mm"2. During first experiments the determined resolution is (76 ± 23) μm using a sample of well-known sharp-edged chromium patterns. Trace element analysis has been performed using a geological sample, a tin ore, with an average Ta-concentration below 0.1 at.%. Fine-zoned structures became visible in the Ta-L_α intensity map within only 45 min. The High-Speed-PIXE closes a gap in the analytical process flow chain especially for geoanalytical characterisations. It is a unique and fast detection system to identify areas of interest in comparably short time at large-area scale for further analysis.

[en] To find the ideal synchrotron radiation induced imaging method for the investigation of trace element distributions in bone tissue, experiments with a scanning confocal micro X-ray fluorescence system and a full-field color X-ray camera setup were performed. In the quest for finding the ideal synchrotron-radiation-induced imaging method for the investigation of trace element distributions in human bone samples, experiments were performed using both a scanning confocal synchrotron radiation micro X-ray fluorescence (SR-µXRF) (FLUO beamline at ANKA) setup and a full-field color X-ray camera (BAMline at BESSY-II) setup. As zinc is a trace element of special interest in bone, the setups were optimized for its detection. The setups were compared with respect to count rate, required measurement time and spatial resolution. It was demonstrated that the ideal method depends on the element of interest. Although for Ca (a major constituent of the bone with a low energy of 3.69 keV for its Kα XRF line) the color X-ray camera provided a higher resolution in the plane, for Zn (a trace element in bone) only the confocal SR-µXRF setup was able to sufficiently image the distribution.

[en] We present a new high resolution X-ray imager based on a pnCCD detector and a polycapillary optics. The properties of the pnCCD like high quantum efficiency, high energy resolution and radiation hardness are maintained, while color corrected polycapillary lenses are used to direct the fluorescence photons from every spot on a sample to a corresponding pixel on the detector. The camera is sensitive to photons from 3 to 40 keV with still 30% quantum efficiency at 20 keV. The pnCCD is operated in split frame mode allowing a high frame rate of 400 Hz with an energy resolution of 152 eV for Mn Kα (5.9 keV) at 450 kcps. In single-photon counting mode (SPC), the time, energy and position of every fluorescence photon is recorded for every frame. A dedicated software enables the visualization of the elements distribution in real time without the need of post-processing the data. A description of the key components including detector, X-ray optics and camera is given. First experiments show the capability of the camera to perform fast full-field X-Ray Fluorescence (FF-XRF) for element analysis. The imaging performance with a magnifying optics (3x) has also been successfully tested.