Yu. G. Lavrent’ev

Some features of X-ray registration using a JXA-8100 electron-probe microanalyzer

Specific sources of measurement errors have been studied. In the presence of perturbing radiation, the automatic setting of the spectrometer discrimination mode is not reasonable. When choosing the transmittance window, the dependence of the shift of the amplitude distribution on the counting rate should be taken into account. Losses of intensity can be significant. The value of effective dead time is 1.3 μs for spectrometers with flow methane-argon counters and 1.2–1.5 μs for spectrometric channels with sealed xenon counters. The mode of constant dead time is retained till the intensities of 100–150 kcps. The instrumental error of routine analysis is insignificant as compared with the statistical error of count collection. In the spectra from LiF crystals, a dip in intensities is adjacent to the shortwave wing of the AuLα radiation line. Measuring intensities on it results in overestimates of the analyte concentration, and line weakening, which occurs because of the spectral hole, in contrast, leads to its underestimation. For this reason, in determining small concentrations of gold, using the Lα line as an analytical one seems unreasonable.

Synthetic TRPO4 crystals as reference samples in the quantitative X-ray electron probe microanalysis of rare-earth elements

Crystals of 15 rare-earth element phosphates, which provide a set of standard reference samples in X-ray electron probe microanalysis, were synthesized and tested for homogeneity and stoichiometry. The phosphates were synthesized in two stages, the preparation of aqueous phosphates and crystal growth in a solution of potassium polymolybdate K2Mo3O10. The tests of the synthesized crystals confirmed their reliability as reference samples.

X-ray electron probe microanalysis in the vicinity of M absorption edges

Nine correction methods with five methods of calculating absorption coefficients are tested for the cases when the analytical line is located in the vicinity of the M adsorption edges of elements with atomic numbers from 76–83. Calculations were performed using the CARAT program and experiments, on the Camebacs Micro microanalyzer. It was found that none of the correction methods can maintain the appropriate accuracy within all absorption ranges. It was proposed to change the μ/ρ ratio in the corresponding inner intervals, which will ensure an accuracy of the analysis at a level of 1 rel %.

Problem of the Account of Matrix Effect in Electron Probe Microanalysis of Rock-Forming Minerals

Four methods of correction and three methods of calculation of absorption coefficients are tested in electron probe microanalysis of rock-forming minerals. Experimental data by Pouchou and Pichoir, Sewell–Love–Scott, and Armstrong are attracted in tests. It is shown that the correction factor can be calculated with the error no more than 1 rel. % if a short-wave line (matrix effect is determined mainly by the effect of atomic number) is used as an analytical line or the analytical line belongs to the absorption K-edge of elements present in the sample. In the presence of binary matrix effect, when the analytical line absorbs in the K–L1 region, the situation is more complex and additional studies are required.

Seventh All-Russia Conference on X-Ray spectrochemical analysis

609 The Seventh All Russia Conference on X ray spec trochemical analysis (XRS) was held on Septem ber 19–23, 2011, in Novosibirsk on the basis of the Sobolev Institute of Geology and Mineralogy of the Siberian Branch of the Russian Academy of Sciences. More than 190 researchers from 29 cities of the Rus sian Federation, Germany, Ukraine, Mongolia, and Kazakhstan registered as participants of the confer ence; 120 of them attended; 37 participants were under the age of 35. The conference was organized by the Scientific Council on Analytical Chemistry of the Russian Academy of Sciences, Sobolev Institute of Geology and Mineralogy of the Siberian Branch of the Russian Academy of Sciences, and the West Siberian Branch of the Russian Mineralogical Society. Finan cial support was provided by the Institute of Geology and Mineralogy and a number of companies: Exiton Analytic, Tokyo Boeki (Rus), Eurotek General, Ana lytical X ray Systems, Termo Tekhno, Moscow Office of Oxford Instruments, Bruker Moscow, Optec, Sistemy dlya Mikroscopii i Analiza, Vysokovol’tnye Sistemy Pitaniya, Synercon, and Melytec (Photo).

New trends in X-ray microanalysis of minerals (Review)

Central tendencies of the development of X-ray microanalysis of minerals are considered. The development of X-ray microanalysis passed through a number of stages. The present stage is characterized by production of computer-controlled microanalyzers capable of maintaining high stability of the electron beam at a high probe current for a long time. This provides powerful technical support of high-current X-ray microanalysis of minerals, which is currently becoming widespread. Microanalysis at high currents and long counting times improves the measurement reproducibility and makes it possible to lower the detection limit in trace analysis.