Hard X-ray phase imaging and tomography using a grating interferometer

An interferometric technique for hard X-rays is presented. It is based on two transmission gratings and a phase-stepping technique, and it provides separate radiographs of the phase and absorption profiles of bulk samples. Tomographic reconstruction yields quantitative three-dimensional maps of the X-ray refractive index and of the attenuation coefficient, with a spatial resolution down to a few microns. The method is mechanically robust, it requires little monochromaticity, and can be scaled up to large fields of view. These are important prerequisites for use with laboratory X-ray sources. Numerous applications ranging from wave front sensing to medical radiography are presently under investigation.     

A new test specimen for the determination of the field of view of small-area X-ray photoelectron spectrometers

Small-area/spot photoelectron spectroscopy (SAXPS) is a powerful tool for the investigation of small surface features like microstructures of electronic devices, sensors or other functional surfaces, and so forth. For evaluating the quality of such microstructures, it is often crucial to know whether a small signal in a spectrum is an unwanted contamination of the field of view (FoV), defined by the instrument settings, or it originated from outside. To address this issue, the d_80/20 parameter of a line scan across a chemical edge is often used. However, the typical d_80/20 parameter does not give information on contributions from the long tails of the X-ray beam intensity distribution or the electron-optical system as defined by apertures. In the VAMAS TWA2 A22 project “Applying planar, patterned, multi-metallic samples to assess the impact of analysis area in surface-chemical analysis,” new test specimen was developed and tested. The here presented testing material consists of a silicon wafer substrate with an Au-film and embedded Cr circular and square spots with decreasing dimensions from 200 μm down to 5 μm. The spot sizes are traceable to the length unit due to size measurements with a metrological SEM. For the evaluation of the FoV, we determined the Au4f intensities measured with the center of the FoV aligned with the center of the spot and normalized to the Au4f intensity determined on the Au-film. With this test specimen, it was possible to characterize, as an example, the FoV of a Kratos AXIS Ultra DLD XPS instrument.     

Laserphotochemistry by holographic grating experiments with quantum limited detection sensitivity and holographic optical information storage by photopolymer systems

Holographic methods are most widely known as techniques for producing three dimensional pictures. However, they can also be used to investigate photochemical and photophysical processes of molecules. Holographic gratings produced by cw and pulsed laser sources have been employed successfully in these investigations during the last decade. In this paper a newly developed holographic grating technique, called phasemodulated holography (PMH), is presented. With this technique for the first time a separated and simultaneous monitoring of the amplitude and phase gratings including the absolute signs of these contributions is possible. Thus, hologram formation mechanisms and the underlying photochemistry can be studied in great detail. This feature and an up to eight orders of magnitude improvement of detection sensitivity (quantum limited detection sensitivity) over conventional techniques makes PMH an ideal tool for the investigation of new materials for holographic optical information storage. This will be demonstrated for several examples i.e. photoactive molecules incorporated in polymer systems.     

A new version of a portable polonium source for the non-destructive PIXE (particle induced X-ray emission) analysis in the cultural heritage field

A new version of the portable polonium source, named L-PIXE (large-particle induced X-ray emission), to be used for the non-destructive analysis in the Cultural Heritage field, was realised in the framework of a collaboration between the Italian LNS-INFN (Laboratori Nazionali del Sud-Istituto Nazionale di Fisica Nucleare) and IBAM-CNR (Istituto per i Beni Archeologici e Monumentali-Consiglio Nazionale delle Ricerche).The new source presents a compact geometry and it was designed to operate with large area SDD (silicon drift detector) detectors. In particular, the L-PIXE source was coupled to a 50 mm² SDD detector and tested by measuring geochemical reference materials.Results evidenced a gain factor, in terms of counting statistics in the measured X-ray spectra, equal to 11–12 with respect to the previous versions of the source. A preliminary evaluation of the MDL (minimum detection limit) of the new experimental set-up evidenced the possibility of using the new L-PIXE source for identifying the presence of minor and, in some cases, trace elements composing samples under investigation.     

光谱分析新光源的完善及发射光谱仪的改造

设计了一种高能火花光源,并用该光源在具有较低电离电位基体中分析有较高激发线的杂质,如ZrO2中Hf;Nb2O5中Ta和MoO3中W,分析灵敏度提高了约10倍。用在较长波段分析气体杂质（如O和C）也是可能的。     

Interest of thick-target bremsstrahlung for an innovative compact X-ray source

A compact X-ray source (1 dm³) has been built, the basis of X-ray production being that of bremsstrahlung (Br) of the hot electrons generated in situ in the core of a hot magnetized plasma. Among the advantages of this device are that it can be pulsed or operated in a stable continuous mode and that there is no requirement for any filament nor high-voltage power supply. Thick-target Br (from a solid material) is involved, first in view of investigating runaway electrons leaking to the lateral walls. Second and more importantly, the features of thick-target Br are exploited in order to make the X-ray source point-like and more intense, a small target being inserted in the way of the hot electrons. The brightness obtained at 20 keV is 3.5×10¹¹ photons s⁻¹ mm⁻² sr⁻¹ keV⁻¹, which for example allows the obtaining of mammographic images in exposure times of a few seconds.     

Analysis of painted steel by a hand-held X-ray fluorescence spectrometer

Steel with a paint layer was analyzed with a hand-held X-ray fluorescence spectrometer. When the 0.5 mm thick paint layer was composed mainly of light elements, alloying elements in steel such as Fe, Cr, Ni, W, and Mo were easily detected. 0.2% Mo in steel was detectable even if the paint contained Ti or Fe as a main element. The signal intensity of each element in steel decreased exponentially when the paint thickness increased, and the degree of decrease depended on the X-ray energy. Therefore the peak intensity for non-painted steel could be calculated from the paint thickness. The paint thickness was estimated from the intensity ratio Fe Kβ/Kα or W Lβ/Lα. When a paint of Ti (0.07–0.49 mm thick) was used, the peak intensities of the Fe Kα, Cr Kα, Ni Kα, and Mo Kα lines for non-painted steel were estimated by using the intensity ratio Fe Kβ/Kα, with errors of less than 30%. The content of each element in steel is estimated when the fluorescent X-rays are detectable by analysis of painted steel without removing the paint layer. On-site screening of painted steel can be performed on the basis of the alloy composition estimated by analysis with a hand-held XRF spectrometer.     

The use of a portable total reflection X-ray fluorescence spectrometer for field investigation

A newly developed, portable total reflection X-ray fluorescence (TXRF) spectrometer was tested during a field campaign on Chilean lakes and a German river in January 2002. The field measurements were compared with laboratory measurements carried out on a stationary instrument in the German laboratory. For method validation certified reference material (NIST SRM 1640 Trace elements in natural water) and water samples from different freshwater sources were analyzed with both techniques and evaluated statistically. Based on these preliminary results, it could be concluded that the portable TXRF is a useful technique for the quantitative elemental screening of freshwater samples during field campaigns. Future tests with biological samples (e.g. biofilms and zooplankton), and suspended matter will provide information about the suitability of the portable TXRF for these materials.     

X-ray absorption near edge structure as a source of structural information

N-(2-Hydroxyethyl)-β-alaninatonickel(II) was synthesized by the interaction of basic nickel carbonate with N-(2-hydroxyethyl)-β-alanine. The structures of the chelating agent and its nickel complex were studied by single crystal X-ray diffraction. In the synthesized compound, the nickel ion lies at the center of an octahedron of the N and 2O donor atoms of two tridentate ligands, each ligand having a meridional conformation. The ligands around the central atom are arranged in perpendicular planes. This coordination of two ligands yields two stereoisomers, whose cocrystallization affords a racemate.     

Determination of zinc in ammoniacal ore leaching solutions by X-ray fluorescence spectrometry using a radioactive source

A method was developed for the fast determination of zinc in leaching solutions by radioisotope energy-dispersive X-ray fluorescence (EDXRF) spectrometry. The measured intensities were used to develop regression models for estimating the zinc concentration. The primary radiation was provided by the ²⁴⁴Cm radioisotope. Several experimental parameters including the saturation thickness and detection limit were determined. The advantages of the utilization of conditioning agents with elements of low atomic number such as nitric acid were established.     

Orientation of molecules by magnetic field as a new source of information on their structures

A complex procedure for quantitative allowance for small but significant effects of molecular orientation by strong static magnetic fields was elaborated. A series of high-resolution ¹H NMR spectra of 1,2,3-trichloronaphthalene recorded at magnetic field strength varied over a wide range was analyzed in the framework of a unified approach with high accuracy. The spin-spin coupling constants and the dipole-dipole coupling constants for all pairs of ¹H nuclei and the anisotropy and rhombicity parameters of the magnetic susceptibility tensor of the molecule were determined. Ab initio CSGT/RHF quantum chemical calculations of this property using a wide range of conventional diffuse and polarization basis set functions were carried out. Augmentation of the basis set with polarization functions affects the values of the calculated parameters to a lesser extent compared to augmentation with diffuse functions. The results of calculations using the 6-311G(df) and 6-311++G(df) basis sets are in good agreement with the experimental values of the magnetic susceptibility anisotropy for 1,2,3-trichloronaphthalene. The advantages of the method proposed and specific features of the effects of orientation by magnetic field as a new source of information on the structure of molecules in solution are discussed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1309–1317, August, 2006.     

X-ray scattering by the phases of 4-methoxybenzylidene-4'-n-butylaniline quenched under a magnetic field

Normally 4-methoxybenzylidene-4'-n-butylaniline exhibits only one liquid-crystalline phase; it is nematic at room temperature. However, after quenching it at liquid nitrogen temperature it is possible to reach four new phases by successive annealing. We report here an experiment aimed at providing a better understanding of these phases by studying their texture after quenching in a magnetic field large enough to orient the sample in the nematic phase.     

Development of a proficiency testing scheme for a limited number of participants in the field of natural water analysis

A proficiency testing (PT) scheme was developed for a limited number of analytical laboratories participating in the analysis of natural water in Israel. Three fit-for-intended-use reference materials (RMs) were prepared for a pilot PT from natural water: RM-blank and two in-house reference materials (IHRMs) with seven analytes fortified to achieve different levels of analyte concentrations. The measurands for the PT participants were the traceable spike values certified in the IHRMs, i.e., added mass concentrations of the analytes. The RM-blank and IHRMs were found to be homogeneous and stable over 11 days, the time necessary for the experimental part of the PT. The RMs were distributed to the PT participants as unknown test items similar to routine samples. The test results were evaluated using their deviations from the IHRM-certified values. Eight Israeli laboratories took part in the interlaboratory comparison. Individual laboratory performance and metrological compatibility of the PT results of the participants, as a local group of laboratories, were evaluated for every analyte.     

Contributions to accuracy improvement of simultaneous ICP atomic emission spectrometry using multi-line measurements of analyte and internal standard elements Applications for the analysis of permalloy

For successful application of simultaneous ICP atomic emission spectrometry for major component determinations in multi-component materials the accuracy of the method has to be improved. As a contribution to solve this problem a combined procedure for multi-component standard sample preparation, optimum calibration and different variations of internal standard corrections is described. Variance-weighted multi-line calibrations give most accurate results. Internal standard corrections are effective, if the time-dependent spectral line intensity fluctuations of the standard and the analyte elements are well correlated. Their sensitivities against some responsible device parameter variations are investigated. On the basis of multi-line measurements of the analyte and internal standard elements a “group-selected internal standard correction” (GS-ISC) method is applied and results in relative errors of less than 1% even for extreme fluctuations of the raw intensities. For rapid routine determination methods of materials with variable element compositions the added line intensities of the internal standard element can be used to correct the added analyte line raw intensities (“intensity addition internal standard correction” (IA-ISC) method). These accuracy optimization procedures are applied for the analysis of the soft magnetic material permalloy using the internal standard element In.     

用X-射线光电子能谱定性和定量分析钴的化学状态

在Ni-MH和Ni-Cd电池制造业中,对钴的价态确定是重要的。高自旋二价钴给出较强的Shake-up伴峰,而三价钴是反磁性的,没有伴峰,由此可以确定钴的价态,并进行定量分析。由实验结果得出下面的经验方程：X%=100（13-20C）/13（C 1）。式中X%是三价钴的百分含量,C是待测样品Co2p1/2Shake-up伴峰与主峰强度之比。此方程可以给出三价钴近似含量。我们从Cop1/2与Shake-up伴峰之间距离或者从伴峰与主峰强度之比,可以鉴别氢氧化亚钴与氧化亚钴。     

Evidence for a bound HeH2 halo molecule by diffraction from a transmission grating

The HeH2 van der Waals complex has been identified in a molecular beam produced by a cryogenic (T0=24.7 K) free jet expansion of a 1% H2 mixture in 99% 4He gas. The weakly bound HeH2 complexes in the beam are identified via their first order diffraction angles after passing through a 100 nm period transmission grating. An electron impact mass spectrometer analysis of the diffraction patterns is used to discriminate against ion fragments of the constituent gas clusters.     

Analysis of nonconforming work as a tool for status analysis and continuous improvement

Absract  The methodology for statistical processing of reports on nonconforming work and unexpected situations which occur in the laboratory of Gamma-Ray Spectrometry Group at the Jožef Stefan Institute is presented. The results of statistical analyses are discussed. Pareto analysis has shown that the majority of cases of nonconforming work originates in errors made by personnel. The sociological and psychological aspects of strategies aimed at preventing careless work are discussed. It is proposed that motivation should be used as a tool against habits that lessen awareness during routine operations. Specific recommendations regarding communication with personnel are given. Received: 20 July 2001 Accepted: 24 October 2001