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This review is devoted to the consideration of prospects and directions for the development of methods and approaches to the analysis of high-purity industrial gases and volatile hydrides, chlorides, fluorides, and organoelement compounds with natural and isotopically enriched compositions. The currently known capabilities for the determination of impurities in them using mass spectrometry, IR spectroscopy, gas chromatography, and chromatography-mass spectrometry are analyzed., Author(s): A. Yu. Sozin [sup.1] , V. A. Krylov [sup.2] , O. Yu. Chernova [sup.1] , T. G. Sorochkina [sup.1] , A. D. Bulanov [sup.1] , A. P. Kotkov [sup.3] [...]

The review is devoted to the capabilities of gas chromatography-mass spectrometry in the analysis of high-purity volatile hydrides of naturally occurring and isotopically enriched compositions. Problems related to experimental techniques, chromatographic separation, identification, and quantitative determination of impurities are discussed. The application of this method has significantly expanded data coverage on the nature, number, and limiting possibilities of the determination of impurities in volatile inorganic hydrides. The identified impurities are compounds of various classes. Among them are atmospheric gases; saturated, unsaturated, and aromatic C.sub.1-C.sub.9 hydrocarbons; chlorine- and fluorine-containing C.sub.1-C.sub.4 hydrocarbons; homologues and alkyl derivatives of hydrides; Si.sub.2-Si.sub.4 siloxanes; fluorosiloxanes; oxygen-containing hydrocarbons; sulfur-containing substances; and hydrides of other elements. Gas chromatography-mass spectrometry analysis made it possible to detect the presence of impurities in isotopically enriched silicon and germanium hydrides, which are their molecular isobars. The use of gas chromatography-mass spectrometry in the analysis of high-purity inorganic hydrides makes it possible to reach the detection limits of impurities of 10.sup.-8-10.sup.-5 mol %., Author(s): A. Yu. Sozin [sup.1], V. A. Krylov [sup.2], O. Yu. Chernova [sup.1], T. G. Sorochkina [sup.1], A. P. Kotkov [sup.3], N. D. Grishnova [sup.3], A. I. Skosyrev [sup.3], G. [...]

The impurity composition of arsine is studied by gas chromatography-mass-spectrometry. Impu-rities of permanent gases; carbon dioxide; hydrides; saturated, unsaturated, and aromatic hydrocarbons C.sub.1-C.sub.6; halogenated hydrocarbons; sulfur compounds; and arsine and diarsine alkyl derivatives are determined. The impurity level of high-purity arsine is 10.sup.-6-10.sup.-5 vol %. Impurity concentrations in arsine after synthesis and in the fractions extracted in the course of its rectification are rather high and lie in the range 10.sup.-6-0.1 vol %. The limits of detection for impurities are 2 x 10.sup.-7-2 x 10.sup.-4 vol %., Author(s): A. Yu. Sozin [sup.1], T. G. Sorochkina [sup.1], O. Yu. Chernova [sup.1], A. P. Kotkov [sup.2], N. D. Grishnova [sup.2], D. M. Polezhaev [sup.2], G. V. Pushkarev [sup.2], S. [...]

The impurity composition of natural and isotopically enriched silane obtained from magnesium silicide and silicon tetrafluoride is studied by gas chromatography-mass-spectrometry. The impurities characteristic of silane with natural and isotopically enriched composition are atmospheric gases; carbon dioxide; hydrides; saturated, unsaturated, and aromatic hydrocarbons; halogenated hydrocarbons; alkyl derivatives and silane homologues, siloxanes. The impurity content of high-purity silane does not exceed 10.sup.-7-10.sup.-5 mol % After synthesis, the concentrations of impurities in the silane and fractions isolated by its distillation purification lie in the range n x 10.sup.-6 - n x 10 mol % The limits of detection for impurities are 1 x 10.sup.-8-9 x 10.sup.-4 mol %, Author(s): A. Yu. Sozin [sup.1], V. A. Krylov [sup.2], O. Yu. Chernova [sup.1], T. G. Sorochkina [sup.1], A. D. Bulanov [sup.1], O. Yu. Troshin [sup.1], A. P. Kotkov [sup.3], N. [...]

A method of chromatography-mass spectrometry is used to study the impurity composition of arsine synthesized by the reaction of arsenic chloride with sodium borohydride. Capillary adsorption columns with adsorbents modified silica and polytrimethylsilylpropine is used for the separation of impurities. Impurities are identified by comparing their mass spectra with the NIST database, published data, as well as by reconstructing their structures from fragment ions. Impurities of permanent gases; saturated and unsaturated hydrocarbons C.sub.1-C.sub.6; chlorinated, oxygenated, and aromatic hydrocarbons; volatile inorganic hydrides; and alkyl derivatives of arsine, trimethyl fluorosilane, carbon sulfur dioxide, and dimethyl sulfide are identified in arsine. Mass spectra of C.sub.2H.sub.3AsH.sub.2, CH.sub.3AsHC.sub.2H.sub.5, and C.sub.2H.sub.5As.sub.2H.sub.3 impurities are obtained for the first time., Author(s): A. Yu. Sozin [sup.1], O. Yu. Chernova [sup.1], T. G. Sorochkina [sup.1], A. P. Kotkov [sup.1] [sup.2], N. D. Grishnova [sup.1] [sup.2], D. M. Polezhaev [sup.2], G. V. Pushkarev [...]

The impurity composition of isotopically enriched germane 70GeH4 was studied for the first time by gas chromatography–mass spectrometry. Impurities were separated using capillary adsorption columns: GS-GasPro (60 m × 0.32 mm) packed with silica gel, GS-CarbonPLOT (25 m × 0.32 mm × 0.25 μm) packed with a carbon sorbent, and a column packed with poly(trimethylsilylpropyne) (25 m × 0.26 mm, df = 0.25 μm)). The use of these columns is shown to provide a high resolution of chromatographed substances. Impurities were identified by comparing their mass spectra with the data of the NIST library. Gases forming a part of the atmosphere, C1–C7 hydrocarbons, chlorine- and oxygen-containing hydrocarbons, sulfur-containing substances, and homologs and alkyl derivatives of germane were detected in germane. As a result of studying the composition of their mass spectra, the mass spectra of impurities 70GeC3H10 and 70GeC4H12, which are absent in the published sources, were obtained and described for the first time. The concentrations of impurities in high-purity germane, as well as their distribution over fractions isolated during the rectification purification of germane, were determined. The limits of detection of the identified substances were 2 ×10–7–1 × 10–4 mol %. [ABSTRACT FROM AUTHOR]

This paper examines sources of carbon impurities in polycrystalline monoisotopic 28Si prepared by a hydride method. Analytical data on the concentrations of carbon-containing impurities in volatile silicon compounds (28SiH4 and 28SiH4), process gases (Ar and H2), and polycrystalline 28Si are used to identify the major sources of carbon in the polycrystalline 28Si prepared by the hydride method. These are the starting 28SiH4 and calcium hydride used in 28SiH4 conversion into 28SiH4. The rate of carbon intake into polycrystalline silicon from the apparatus material during the monosilane pyrolysis process does not exceed 9 × 1011 cm-2 h-1. Polycrystalline silicon has been precipitated from monosilane with different concentrations of hydrocarbon impurities. At hydrocarbon concentrations in the range 10-4 to 10-3 mol %, the carbon concentration in the monosilane correlates with that in the silicon obtained from it. High-purity monosilane has been used to prepare polycrystalline 28Si samples with concentrations of carbon impurities in the range (0.8-2.3) × 1015 cm-3. Based on calculations of the carbon impurity distribution along the length of a zone-refined ingot, we examine the effect of the initial carbon concentration in the starting polycrystal on the yield of single-crystal monoisotopic 28Si. Requirements are formulated for the carbon concentration in polycrystalline 28Si which ensure a high yield of single crystals with parameters suitable for metrological applications. [ABSTRACT FROM AUTHOR]

The procedure for gas-chromatographic determination of hydrocarbons and sulfur tetrafluoride in germanium tetrafluoride of natural and isotopically enriched composition was characterized. For improving the efficiency of the chromatographic determination of impurities, it was proposed that the major compound be removed from the test sample with the subsequent cryofocusing of impurity hydrocarbons. The detection limits of C1–C4 and sulfur hexafluoride content were achieved with a plasma ionization detector and electron-capture detector, respectively. They amounted to (2–6) × 106 vol % and 8 × 106 vol %, respectively. The sensitivity of the electron-capture detector is no less than 5 × 105 times higher toward SF6 than that toward hydrocarbons, while the plasma ionization detector is 104 times more sensitive toward hydrocarbons than toward SF6. [ABSTRACT FROM AUTHOR]

We have developed analytical techniques for the determination of impurities in isotopically enriched 28SiH4 and 28SiF4. The impurities in SiF4 were first determined by IR spectroscopy, and those in SiH4, by gas chromatography/mass spectrometry. High-sensitivity determination of organic impurities in SiH4 and SiF4 was performed by gas chromatography. SiF4 was found to contain C1–C4 hydrocarbons, hexafluorodisiloxane (Si2F6O), hydrogen fluoride, trifluorosilanol (SiF3OH), fluorosilanes, water, and carbon oxides. The impurities identified in SiH4 include C1–C4 hydrocarbons, disilane (Si2H6), inorganic hydrides, Si2H6O, alkylsilanes, and fluorinated and chlorinated organics. The detection limits of IR spectroscopy were 3 × 10−3 to 5 × 10−5 mol %, those of gas chromatography/mass spectrometry were 8 × 10−6 to 10−8 mol %, and those of gas chromatography were 6 × 10-6 to 2 × 10−7 mol %. [ABSTRACT FROM AUTHOR]