Narrow Results

Chemical shifts of Kα_1,2 line of sulfur in marine sediments were measured with in-air high-resolution PIXE in order to examine the possibility of direct speciation of sulfur in such environmental substances. Change of chemical states of sulfur along the depth in the sediments was observed. Oxidation of the sediment samples by air was also examined. Problems to be improved for exact speciation are discussed.

The paper presents the verification of home made Position Sensitive Spectrometer (PSS) while using synchrotron radiation light (SRL) as an excitation source. When Cr in the substance of light base was analyzed by the PSS, the lowest detection limit of a few ppm was achieved. Also linear proportionality between the count rate of the PSS and Cr concentration was obtained. This verities the feasibility of trace element analysis with high-energy resolution when using the PSS. At measurement of Cr Kβ₅ band in metallic Cr and its compounds, it was discerned that the intensity of Cr Kβ₅ becomes more intense with increasing oxidation number of Cr compounds. Such a change shows that high-energy resolution analysis using the PSS can make a useful method for the study of chemical states.

The feasibility of RIKEN high-resolution PIXE system for direct chemical state analysis of 3d transition elements was examined. Kβ spectra of Cr and Fe from several compounds were measured in air at atmospheric pressure using a crystal spectrometer consisting of a position-sensitive proportional counter and a curved crystal in v. Hamos geometry. Fine structures which reflect the chemical states of Cr and Fe were well recognized with the measuring time of tens minutes.

Ion-Beam-Induced Luminescence (IBIL) spectra and images for the chemical states and crystal structures of micrometer-sized mineral targets were obtained by wavelength-dispersive IBIL analysis. A wavelength resolution of approximately 2 nm was achieved with a remote-controlled compact monochromator installed on an IBIL analysis system using a 3 MeV H⁺ microbeam. Several particulate mineral targets and aerosol samples were prepared on a carbon-plate sample holder that was selected to reduce the background noise and achieve a high S/N ratio in both the IBIL and Particle-Induced X-ray Emission (PIXE) analyses. The chemical composition of small targets that could not be well determined using micro-PIXE analysis was successfully visualized by the proposed IBIL analysis.

A soft X-ray crystal spectrometer designed for chemical state analysis by PIXE is described. A windowless, microchannel plate (MCP) electron multiplier combined with a photodiode array was used as a position-sensitive detector for X-rays diffracted by a plane crystal. The spectrometer was tested for Al Kα and Fe L X-ray spectra induced by 15 MeV N²⁺ ion impact. An energy resolution (FWHM) of 1.5 eV for the 1487 eV Al Kα_{1, 2} line was obtained for metallic Al, and satellite structures of Al Kα arising from multiply ionized states were well resolved. Fe L X-ray spectra were measured for Fe₂O₃ and metallic Fe. Chemical effects were clearly recognized in the Fe Lα/Lβ intensity ratio and in the intensity distributions of their multiple vacancy satellites.

We describe characteristics of high-resolution, wavelength-dispersive crystal spectrometers equipped with a different type of position sensitive X-ray detectors: PSPC, CCD, IP and MCP. Utilities of these position sensitive spectrometers in PIXE experiments are demonstrated by referring several recent topics of elemental analysis, chemical state analysis and a study on sample charging.

A position-sensitive proportional counter (PSPC) for a wavelength-dispersive crystal spectrometer system has been constructed for high-resolution PIKE experiments in atmospheric air. This PSPC has seven resistive wire anodes. Each anode operates as one PSPC. Pulses from the anodes are converted into digital signals with a 512 × 7 channel charge-division analyzer. We can simultaneously obtain seven spectra. A computer software converts this 2D data set into one spectrum after adjusting the offset channels and conversion factors. The spatial resolution of this detector is somewhat larger than that of our single PSPC system previously developed, while its counting efficiency is seven times higher than that of the single one.

Performance of a micro WDX-PIXE system that consists of position sensitive x-ray spectrometer and the heavy ion microbeam line is described. The influence of the position resolution of the position sensitive proportional counter (PSPC) used in the spectrometer on system energy resolution is discussed based on the measured values for C and O K x-rays. The system has successfully been used for chemical state analysis of various compound materials and small area of the materials (< 3 × 10^-3mm²) can be analyzed.

In this review (in continuations) X-ray crystal spectrometers working on ion beams and their applications are surveyed. The present fourth part continues to describe: (i) their use for elemental analysis; (ii) their use for obtaining the information about the chemical effects in the Particle Induced X-ray Emission spectra; (iii) their use in basic research for obtaining information applied in the above relations and their applications on acelerators. We update the data of formerly discussed systems according to the changes in the world.