Kazuhiko Nakano

Depth Elemental Imaging of Forensic Samples by Confocal micro-XRF Method

Micro-XRF is a significant tool for the analysis of small regions. A micro-X-ray beam can be created in the laboratory by various focusing X-ray optics. Previously, nondestructive 3D-XRF analysis had not been easy because of the high penetration of fluorescent X-rays emitted into the sample. A recently developed confocal micro-XRF technique combined with polycapillary X-ray lenses enables depth-selective analysis. In this paper, we applied a new tabletop confocal micro-XRF system to analyze several forensic samples, that is, multilayered automotive paint fragments and leather samples, for use in the criminaliztics. Elemental depth profiles and mapping images of forensic samples were successfully obtained by the confocal micro-XRF technique. Multilayered structures can be distinguished in forensic samples by their elemental depth profiles. However, it was found that some leather sheets exhibited heterogeneous distribution. To confirm the validity, the result of a conventional micro-XRF of the cross section was compared with that of the confocal micro-XRF. The results obtained by the confocal micro-XRF system were in approximate agreement with those obtained by the conventional micro-XRF. Elemental depth imaging was performed on the paint fragments and leather sheets to confirm the homogeneity of the respective layers of the sample. The depth images of the paint fragment showed homogeneous distribution in each layer expect for Fe and Zn. In contrast, several components in the leather sheets were predominantly localized.

Development of a new confocal 3D-XRF instrument with an X-ray tube

A new 3D-XRF instrument was developed with a fine-focus X-ray tube. The depth resolution of the developed instrument was 13.7 µm at the energy of Au Lβ (11.4 keV). Compared with the previous 3D-XRF instrument developed in the authors research group, the depth resolution was improved by a factor of 3–4. A small dependence of depth resolution on X-ray energy was also confirmed for the new instrument. The depth resolution was varied from 22.6 µm to 13. 7 µm for an energy range from 5.4 keV to 11.4 keV, respectively. A few layered materials were measured by two (previous and new) 3D-XRF instruments. As expected, the new 3D-XRF instrument gave a depth profile with a high-resolution. In addition, a 3D-structured material was proposed and developed to evaluate the 3D-imaging performance. The material consisted of two cylindrical patterns of Au having a micrometre-scale structure. Elemental imaging performance was compared by using this 3D-structured material for two different 3D-XRF instruments.

Development of laboratory confocal 3D-XRF spectrometer and nondestructive depth profiling

The present paper reports on the laboratory 3D-XRF results applied to industrial and environmental samples. The feasibility of confocal 3D-XRF analysis was characterized with regard to the depth resolution and depth sensitivity. To investigate the depth sensitivity of the confocal 3D-XRF analysis, the multilayered plastic reference samples were prepared by using a spin coating method. It was confirmed that these plastic layered reference materials were useful for evaluating the analytical performance of confocal 3D-XRF. In addition, many applications of 3D-XRF to industrial plastics, chemical microchip, and biological samples were demonstrated under the confocal XRF configuration.

Comparison of two confocal micro‐XRF spectrometers with different design aspects

Two different confocal micro X-ray fluorescence spectrometers have been developed and installed at Osaka City University and the Vienna University of Technology Atominstitut. The Osaka City University system is a high resolution spectrometer operating in air. The Vienna University of Technology Atominstitut spectrometer has a lower spatial resolution but is optimized for light element detection and operates under vacuum condition. The performance of both spectrometers was compared. In order to characterize the spatial resolution, a set of nine specially prepared single element thin film reference samples (500 nm in thickness, Al, Ti, Cr, Fe Ni, Cu, Zr, Mo, and Au) was used. Lower limits of detection were determined using the National Institute of Standards and Technology standard reference material glass standard 1412. A paint layer sample (cultural heritage application) and paint on automotive steel samples were analyzed with both instruments. The depth profile information was acquired by scanning the sample perpendicular to the surface.

Micro and imaging x-ray analysis by using polycapillary x-ray optics

We have studied the micro x-ray fluorescence (XRF) and 2D- or 3D-XRF analysis in the laboratory by using polycapillary optics. A confocal 3D micro-XRF instrument was applied for solid/liquid interface analysis. 2D elemental maps of x-ray fluorescence for the solid surface of an Fe plate after Cu was deposited by chemical plating were obtained. The 2D images could be taken in the solution. This result suggests that this 3D micro-XRF method is useful for in-situ monitoring of chemical reactions on solid-liquid interfaces. Furthermore, we have reported a new application of polycapillary x-ray optics. Two independent straight polycapillary optics were arranged between the sample and an x-ray energy dispersive detector. X-ray fluorescence emitted from the sample was collimated by the first capillary, and then it was introduced into the second capillary. By adjusting the angle between two capillary optics, only the x-rays totally reflected on the inner wall of the second capillary could be detected by the x-ray detector. This result suggests that we can use these polycapillary optics for x-ray energy filtering optics.

Preconcentration of Environmental Waters by Agar for XRF Analysis

We have developed a convenient and effective XRF analysis procedure for trace amount of K, Ca, V, Mn, Fe, Ni, Cu, Zn, Cd, and Pb in environmental waters by using a preconcentration using the natural polymer (agar). The thin agar film was prepared by drying a homogeneous agar gel after mixing the aqueous sample solution with the agar powder. XRF analysis of the preconcentrated thin agar films containing trace metals showed a good repeatability, because agar films were homogeneous enough. SB (signal to noise) ratios of the XRF intensity of the analytes were improved drastically. The linear calibration curves of K, Ca, V, Mn, Fe, Ni, Cu, Zn, Cd, and Pb showed a good linearity within the calibration ranges. The lower limits of detection (LLD) were 1.4 ∝g/mL for K, 0.26 ∝g/mL for Ca, 0.088 ∝g/mL for V, 0.029 ∝g/mL for Mn, 0.11 ∝g/mL for Fe, 0.016 ∝g/mL for Ni, 0.030 ∝g/mL for Cu, 0.017 ∝g/mL for Zn, 0.20 ∝g/mL for Cd, and 0.066 ∝g/mL for Pb, respectively. The proposed preconcentration method was applied to several environmental water samples.

Enhancement of XRF intensity by using Au-coated glass monocapillary

Enhancement of XRF intensity was investigated by using an Au coated glass-capillary. Au was electroplated on an inner wall of the glass-capillary with a thickness of 100 nm. The Au coated glass-capillary was attached to a micro focus x-ray tube. The XRF intensity from the pure metal samples was measured by a silicon drift x-ray detector. It was confirmed that the intensity of XRF was enhanced by using Au coated glass-capillary by factors of 1.1 to 1.5 times. The XRF intensity profile was also measured by wire scanning method to investigate the reason. The trace of primary x-ray beams was calculated considering x-ray total reflection. The calculated results of agreed well with the experimental XRF intensity profile. The reason of enhancement XRF intensity was that the primary x-rays were totally reflected on the inner wall of

F-47 TXRF and Micro-XRF Analysis of Plastic Toys and Soils

A gas turbine system includes a gas turbine engine configured to combust a fuel and produce an exhaust gas. An exhaust duct assembly is coupled to the gas turbine engine and is configured to receive the exhaust gas. An absorption chiller is fluidly coupled to the exhaust duct assembly and is configured to receive a take-off stream of the exhaust gas. The absorption chiller is configured to use the take-off stream to drive at least a portion of an absorption cooling process to generate a cooled take-off stream of exhaust gas. The exhaust duct assembly is configured to receive the cooled take-off stream of exhaust gas from the absorption chiller and to mix the cooled take-off stream with exhaust gas present within the exhaust duct assembly to cool the exhaust gas.

F-20 APPLICATIONS OF POLYCAPILLARY OPTICS TO MICRO AND TWO DIMENSIONAL XRF ANALYSIS

The analysis of small regions of a sample has become one of the significant trends in x-ray fluorescence spectrometry (XRF) studies. XRF has been applied to micrometer-scale analysis (micro-XRF) by using various focusing x-ray optics in the laboratory. We have studied applications of micro-XRF with polycapillary x-ray lens [1-3]. The micro x-ray beam less than 0.01 mm, however, were hard to achieve by using the polycapillary x-ray lens, because this is limited by the “halo effect” [4]. In this study, we investigated that a new optics system for micro-XRF instrument combined capillary optics, such as the polycapillary x-ray lens and the x-ray guide tube or the single capillary. The polycapillary x-ray lens was attached to an x-ray tube (Mo tube). A spot size of 0.07 mm was obtained at the output focal distance. This micro x-ray beam was collimated by using the x-ray guide tube or the single capillary, and the beam size was be decreased to about 0.02 mm with reasonable intensity. Another application of the polycapillary optics will also be presented.

Ultrahigh-capacity multidata layer ROM

We have developed an ultra-high-capacity double-sided multi- data-layer ROM that includes additional UV-cured-resin space-layers on two polycarbonate (PC) substrates. This ROM is made using the photo-polymerization (2P) method and has a structure that bonds the two substrates together. In a double-sided dual-data-layer ROM, using the smallest mark size of 0.44 micrometers with a 0.74-micrometer track-pitch for each layer provides a total data capacity of 17 GB using the 8-16 modulation method. Each side of the double-sided dual-sided dual-data-layer ROM consists of a Si-rich silicon nitride semi-reflective layer (layer 0 or 2) on a 570- micrometers-thick PC substrate and an Al reflective layer (layer 1 or 3) on an additional 50-micrometer-thick space layer. We achieved a base jitter of less than 8 percent and a radial tilt margin of 0.7 degree for all four data layers. We also examined the double-sided multi-data-layer ROM disc structure, and demonstrated the feasibility of the double- sided tri-data-layer ROM that includes a total of six layers and has an ultra-high capacity of 25.5 GB.