Shinsuke Kunimura

HANDY WAVEGUIDE TXRF SPECTROMETER FOR NANOGRAM SENSITIVITY

A specimen containing nanograms of sulfur, calcium, and 3d transition metal elements was measured by incident X-ray beams of various sizes restricted by a waveguide placed in a portable TXRF spectrometer. The signal to background ratios of spectra decreased with an increase in incident X-ray beam size. The portable spectrometer was also applied to rainwater and a specimen containing antimony and rare earth elements. Nanograms of elements in these specimens were detected by K-line or L-line excitation.

Portable TXRF Spectrometer with 10{sup -11}g Detection Limit and Portable XRF Spectromicroscope with Sub-mm Spatial Resolution

A portable total reflection X‐ray fluorescence (TXRF) spectrometer that we have developed is applied to trace elemental analysis of water solutions. Although a 5 W X‐ray tube is used in the portable TXRF spectrometer, detection limits of several ppb are achieved for 3d transition metal elements and trace elements in a leaching solution of soils, a leaching solution of solder, and alcoholic beverages are detected. Portable X‐ray fluorescence (XRF) spectromicroscopes with a 1 W X‐ray tube and an 8 W X‐ray tube are also presented. Using the portable XRF spectromicroscope with the 1 W X‐ray tube, 93 ppm of Cr is detected with an about 700 μm spatial resolution. Spatially resolved elemental analysis of a mug painted with blue, red, green, and white is performed using the two portable spectromicroscopes, and the difference in elemental composition at each paint is detected.

Note: Portable total reflection X-ray fluorescence spectrometer with small vacuum chamber.

To improve the detection limits of a portable total reflection X-ray fluorescence (TXRF) spectrometer using white X-rays (i.e., both characteristic X-rays and continuum X-rays) from a 5 W X-ray tube, the measurement was performed in vacuum. The TXRF spectrum measured in vacuum was compared with that measured in air. The spectral background was significantly reduced when the scattering of the incident X-rays from air was reduced using a vacuum pump, leading to improvement in the detection limit. A detection limit of 8 pg was achieved for Cr when measuring in vacuum.

Multilayer nano-thickness measurement by a portable low-power Bremsstrahlung X-ray reflectometer

A low-power (1.5 W) portable Bremsstrahlung X-ray reflectometer (XRR) has been designed, realised and tested. The purpose of this apparatus is to measure thicknesses of multilayers within an X-ray beam energy range of 1–9.5 keV in industrial and research environments. Experiments have been carried out in this range with a measurement time of 10 min. The reflectometer apparatus was set up aligning the X-ray tube, sample holder and Si-PIN detector in one plane. A Mo/Si (9.98 nm) multilayer sample was used in the measurement. The direct beam intensity at (0.00°) was measured. Intensity was measured at several glancing angles and reflectivity was calculated. Although one measurement is sufficient in a dispersive energy X-ray reflectometer (XRR), measurement was taken at 0.45°, 0.60° and 0.80°. The sample was tilted at an angle θ and the detector was linearly elevated corresponding to 2θ at each measurement. A calibration equation was proposed to fit the apparatus geometry. Experimental reflectivity was calculated and compared to theoretical results. The portable X-ray reflectometer (XRR) was proved feasible in multilayer nano-thickness measurement.