微区X射线衍射在矿物鉴定中的应用实例

介绍了微区X射线衍射仪发展的现状,给出了微区X射线衍射仪鉴定物相的研究实例,并讨论了微区X射线衍射法的优、缺点。通过配置有封闭3kWX射线光管、单毛细管透镜、Pixcel探测器和普通CCD视频的Panalytical X’Pert PRO MPDX射线衍射仪,对光片上的铍矿物进行了微区X射线衍射鉴定,结果确定该铍矿物为羟硅铍石。微区X射线衍射法具有微区、微量、原位和无损等优点,能够进行直径在100～300μm范围内的两种或两种以上矿物集合体的物相鉴定。与电子探针等微区手段相互结合、互相补充,鉴定结果更加可靠。     

微量石棉的X射线衍射定量检测

微量(质量分数低至0.1%)石棉的定量分析是一世界性难题。研究了自行车、电动车车闸等摩擦材料中石棉含量为0.1%~5.0%(质量分数)的X射线衍射定量分析方法。对含有微量石棉的样品通过X射线衍射的基底吸收修正法,求出定量分析试样中的石棉含量,计算出石棉的比例。研究成果对支持我国自行车、电动车等产品出口日本的工作具有现实意义。     

田黄的X射线衍射研究

用X射线衍射分析的方法测定了12个田黄样品,其中,青田石1个,寿山石9个,昌化田黄石2个。确定青田石由叶蜡石(58%)、绢云母(36.1%)和高岭石(5.9%)组成;昌化田黄石由迪开石组成;寿山石分别由迪开石、高岭石、叶蜡石及绢云母组成。     

Raman spectra of nitrogen-containing organic compounds obtained in high altitude sites using a portable spectrometer: Possible application for remote robotic Titan studies

Well-resolved Raman spectra of examples of nitrogen-containing compounds were detected using a portable Raman instrument (Ahura First Defender XL) outdoors at a low temperature of −15 °C at an altitude of 2860 m (Pitztall, Austria). The portable Raman spectrometer tested here is equipped with a 785 nm diode laser and fixed frontal probe. Solid forms of formamide, urea, 3-methylpyridine, aniline, indene, 1-(2-aminoethyl)piperazine, benzofuran and indoline were detected unambiguously under field high-mountain conditions. The main Raman features (strong, medium and partially weak bands) were observed at their correct wavenumber positions (spectral resolution 7-10 cm⁻¹) in the range 200-2000 cm⁻¹. The results obtained demonstrate the possibility of applying a miniaturised Raman spectrometer as key instrument for investigating the presence of nitrogen-containing organic compounds and biomolecules under low temperature field conditions. Within the payload designed by ESA and NASA for future missions focusing not only on Mars, Raman spectroscopy will be an important non-destructive analytical tool for the in-situ identification of both organic and inorganic compounds relevant to life detection on planetary surfaces or near sub-surfaces.     

X-ray Spectromicroscopy of Mineral Intergrowths in the Santa Catharina Meteorite

This work describes the application of microfocus X-ray absorption spectroscopy (XAS) and X-ray photo-emission electron microscopy (XPEEM) to the study of the complex mineralogical intergrowths within the Santa Catharina meteorite. The Santa Catharina meteorite of this study (BM52283 from the meteorite collection of the Natural History Museum, London, UK) primarily comprises a taenite bulk host phase (Fe:Ni ratio = 70.9 ± 0.8%:29.1 ± 0.8%) with a set of oxide-bearing cloudy zone textured regions (Fe:Ni:O ratio = 40.4 ± 0.3%:49.0 ± 0.7%:10.6 ± 0.8% at the core and Fe:Ni:O ratio = 34.4 ± 1.5%:42.7 ± 0.6%:22.9 ± 1.8% towards the rims) and numerous schreibersite (Fe:Ni:P ratio = 38.6 ± 1.6%:38.4 ± 0.9%:23.0 ± 0.5%) inclusions. Between the schreibersite and the taenite are rims up to 50 μm across of Ni-rich kamacite (Fe:Ni ratio = 93.4 ± 0.4%:6.6 ± 0.5%). No chemical zoning or spatial variations in the Fe and Ni speciation was observed within either the schreibersite or the kamacite phases. The oxide-bearing cloudy zone textured regions mostly comprise metallic Fe–Ni alloy, predominantly tetrataenite. Within the oxide phases, the Fe is predominantly, but not entirely, tetrahedrally co-ordinated Fe³⁺ and the Ni is octahedrally co-ordinated Ni²⁺. Structural analysis supports the suggestion that non-stoichiometric Fe₂NiO₄ trevorite is the oxide phase. The trevorite:tetrataenite ratio increases at the edges of the oxide-bearing cloudy zone textured regions indicating increased oxidation at the edges of these zones. The spatial resolution of the XPEEM achieved was between 110 and 150 nm, which precluded the study of either the previously reported ∼ 10 nm precipitates of tetrataenite within the bulk taenite or any antitaenite.     

Copper Mosaic Crystals for Laue Lenses

Large single crystals of copper with an uniform and very narrow mosaic spread between 25 seconds and 1 minute of arc are now available at I.L.L. This result is of great interest in the construction of a Laue lens for astrophysical applications for which such quality copper single crystals may be used. The X-ray diffraction properties of copper single crystals produced at I.L.L. were studied for x-ray energies ranging from 100 keV to 400 keV. Several monocrystalline plates with different thicknesses and mosaic distributions were then prepared from the as-grown crystals in order to measure their diffraction efficiency as a function of energy. As expected, the value of the peak reflectivity depends on the crystal thickness. Reflectivity measurements show the excellent properties of copper crystals for gamma-ray diffraction. A peak reflectivity of 24% was measured at 220 keV from a copper single crystal of 3.75 mm thickness having a mosaic spread of 1.5 minutes of arc. Some technical aspects on the preparation of copper single crystal plates are also discussed.     

伴有OH 1720 MHz脉泽发射的混合形态超新星遗迹的X射线特征研究

在银河系中，超新星遗迹的射电巡视揭示了19个伴有OH1720MHz脉泽发射的超新星遗迹．在从超新星遗迹膨胀到分子云的激波波面的后面产生了这一类不寻常的脉泽源．这个模型的重要点是从超新星遗迹来的X射线促使产生OH分子．研究伴有OH1720MHz脉泽发射的混合形态超新星遗迹的X射线特征是很重要的．研究了这19个伴有OH1720MHz脉泽发射的混合形态超新星遗迹的X射线特征．得到了这些源的X射线物理参数之间的一些相关关系和反相关关系．X射线电离率ζ与θ、D、r、r^2等物理量均不相关，而与Lx之间存在着正相关关系．另外超新星遗迹的X射线光度与相伴的OH1720MHz脉泽的最弱的束流量密度之间存在着紧密的正相关关系．这些都说明从超新星遗迹来的X射线发射足够在激波波阵面后面分解水分子并产生OH1720MHz脉泽．     

Spectroscopy of Galaxies in Selected Fields of the Second Byurakan Survey

Spectroscopic data are presented for 35 galaxies from selected fields of the Second Byurakan Survey (SBS). The observations were made on the 2.6 m telescope at the BAO using the SCORPIO spectral camera. A majority of the objects were observed for the purpose of improving the classification of types in accordance with an adapted scheme presented in this paper.     

A hard X-ray sky survey with the SIGMA telescope of the GRANAT observatory

The SIGMA X-ray telescope accumulated the images of more than a quarter of the sky during the in-orbit operation of the GRANAT observatory. The longest exposure time (～9 million s) was spent on the observations of the Galactic center region. We give an overview of the SIGMA X-ray observations and report the sensitivities achieved in various regions of the sky.