Toshio Ishizuka

X-ray photoelectron spectroscopy of rare-earth compounds

Abstract A variety of rare-earth (RE) compounds (oxides, sulfates and oxalates) have been studied by X-ray photoelectron spectroscopy. Except for Eu, the binding energies (BEs) of the RE 3 d and 4 d peaks for the sulfates and oxalates are respectively almost equal to and 1.3–3.1 eV higher than those for the oxides. In the Eu 3 d spectrum of europium(II) oxalate, distinct shake-down satellite peaks are present, and the BEs of these peaks are 10 eV lower than the parent ones. For the oxides, appreciable differences are found in the BEs of the O 1 s peaks, and a specific “inclined W” form is observed in plots of BE versus 1/ R (where R is the mean distance from the oxygen atom to the neighboring RE atom) and versus the RE oxidation-reduction potential (ORP). No characteristic differences are seen in the BEs (C 1 s , S 2 s and S 2 p ) of the other ligands.

Elution behaviour of acids in ion-exclusion chromatography using a cation-exchange resin

Abstract A large number of strong and weak acids have been subjected to ion-exclusion chromatography by elution with water on a hydrogen-form cation-exchange resin. The column void volume (Vo) and inner volume (Vi) were determined from a calibration graph obtained by plotting the retention volumes (VR) against the first dissociation constants (pKP1) of the acids. The distribution coefficients (Kd) of the acids were calculated from the conventional equation for ion-exclusion chromatography: VR = Vo + KdVi. As the Kd values of most acids are between 0 and 1, it is possible to evaluate by gel chromatography the separation mechanism of acids based on the ion-exclusion effect.

Charge correction by gold deposition onto non-conducting samples in X-ray photoelectron spectroscopy

Abstract Gold deposited onto sample materials has been used as a calibrant for determining their absolute binding energies, and the optimum thickness of the gold decoration investigated. Polytetrafluoroethylene film and NaF and graphite pellets were used as the substrate materials. A series of depositions of gold layers up to ∼60 A thick was performed on each sample surface. The thickness of gold deposited influences the apparent binding energies, the precision of the charge-corrected binding energies, and the FWHMs of the Au 4f, C 1s and F 1s peaks. It seems that, for the instrument used in this study (which records photoelectrons at 45° to the sample surface), the optimum thickness of gold deposited onto a non-conducting sample surface is ∼ 6 A (ie., ∼9 A path-length through the layer).

Determination of trace inpurities high-purity aluminum oxide by inductively-coupled plasma atomic emission-spectrometry

Abstract Trace impurities (Ca, Cu, Fe, Mg, Mn, Na and Si) in 99.99% aluminum oxide were determined by inductively-coupled plasma atomic emission spectrometry (i.c.p./a.e.s.). The sample was fused with lithium carbonate/boric acid to determine Ca, Cu, Mg, Mn, Na and Si or dissolved in phosphoric/sulphuric acids to determine iron. Matrix effects on the calibration graphs for each element were studied: for accurate determinations, calibration solutions must contain lithium and boric acid (or aluminium and phosphoric and sulphuric acids for iron).

Quantitative Analysis of Powdery Sample by Diffuse Reflectance Infrared Fourier Transform Spectrometry: Determination of the α-Component in Silicon Nitride

An application of diffuse reflectance infrared Fourier transform (DRIFT) spectrometry to determine powdery sample with an unknown particle size has been proposed. The usefulness of this technique has been demonstrated for the analysis of the α-component in Si3N4 powders. The particle size of the α-component in Si3N4 powder could be determined by measuring the peak intensity ratio between two peaks (500 and 690 cm−1) on the DRIFT spectrum, and the concentration could be determined by comparing the peak intensity to that of standard α-Si3N4 with same particle size. The particle sizes and concentrations obtained by the DRIFT method were in good agreement with those obtained by the light-scattering method and x-ray diffractometry, respectively.

Ion-exclusion chromatography of condensed phosphates on a cation-exchange resin

The ion-exclusion chromatography of orthophosphate (PO43−) and several condensed phosphates (P2O74−, P3O105− and P3O92−) was investigated using a cation-exchange resin column in the H+ form. The phosphates eluting from the column were monitored as the corresponding acids with flow coulometric and conductometric detectors. The retention volumes of the phosphates increased with increase in the concentration of organic solvents (acetone and dioxane) in the eluent, and the increases were greater in water-dioxane than in water-acetone. A good separation of the phosphates from each other could be achieved by gradient elution with 80% dioxanewater.

Determination of Silicon Dioxide in Silicon Carbide by Diffuse Reflectance Infrared Fourier Transform Spectrometry

Diffuse reflectance infrared Fourier transform spectrometry was applied to the determination of SiO2 in SiC powders. The main peaks of SiO2 were observed in the 1000–1250 cm−1 region. The peak intensities were estimated from the peak height at 1150 cm−1. The intensities were little affected by the particle sizes of SiC powders in the 1–9–μm region. The linear relationship between peak intensity and concentration was obtained in the concentration range of 0–5 wt% SiO2. The analytical curve was successfully used for the determination of SiO2 in a few commercial SiC powders.

Determination of phosphorus in waste-waters by inductively-coupled plasma atomic emission spectrometry

Abstract Inductively coupled plasma—atomic emission spectrometry offers a simple and rapid method for the determination of total phosphorus in waste-waters: the optimum operating conditions are described. The detection limits are 0.02, 0.04, and 0.11 μg ml-1 at the 213.618, 214.914, and 253.565-nm lines, respectively. Interferences by other elements are negligible at the concentration levels of these elements in environmental and waste-waters, except for the spectral interference of copper on the lines at 213.618 and 214.914 nm. Differences in emission response for various inorganic and organic phosphorus compounds are small. Analytical results for phosphorus in municipal and industrial waste-waters agree well with those obtained by standard methods.

Ion-exclusin chromatography of the ammonium ion on an anion-exchange resin

Abstract Ion-exclusion chromatography of NH 4 + has been investigated on an anion-exchange resin (OH − ). NH 4 + was chromatograhed by ion exclusion as NH 4 OH formed by anion exchange, and monitored with a flow coulometric detector for the detection of OH − , and / or with a conductometric detector The chromatographic conditions for the separation of NH 4 + from diverse cations, the separation mechanism and each detector response are discussed. This method has been applied to the determination of NH 4 + in sewage and river water. The result obtained agree well with those obtained by the phenate method.

Laser ablation in a liquid medium as a technique for solid sampling

A new technique for solid sampling, laser ablation in a liquid medium, has been developed and evaluated. A solid sample was held in a liquid medium contained in a flat-bottomed beaker. Laser pulses from a Q-switched Nd:YAG laser were introduced from the bottom of the beaker and were focused on the surface of the solid sample. Both the vapour and the particles produced by the laser ablation were trapped directly by the surrounding liquid, and a suspension was formed. The technique offers both time and spatial separation of the sampling and introduction and excitation processes in the laser ablation. The morphological observation of trapped particles, the evaluation of trapping efficiency and fractional ablation, and the direct introduction of the suspension into an inductively coupled argon plasma were carried out. Nearly 100% trapping efficiency and the absence of fractional ablation were obtained.