Molybdenum X-Ray Absorption Edges from 200 – 20,000 eV, The Benefits of Soft X-Ray Spectroscopy for Chemical Speciation
Molybdenum X-Ray Absorption Edges from 200 – 20,000 eV, The Benefits of Soft X-Ray Spectroscopy for Chemical Speciation
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发表时间：
2010
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通讯作者：
S. George;O. Drury;Juxia Fu;S. Friedrich;J. Christian;Doonan;G. George;J. White;Charles G. Young;P. Stephen;Cramer
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作者：
S. George;O. Drury;Juxia Fu;S. Friedrich;J. Christian;Doonan;G. George;J. White;Charles G. Young;P. Stephen;Cramer
我们调查了钼 X 射线吸收边的近边结构的化学效用，从 20,000 eV 的硬 X 射线 K 边到约 230 eV 的软 X 射线 M 4,5 边。我们针对每条边比较了两种四面体阴离子 MoO 4 和 MoS 42- 的光谱。我们使用三个标准来评估每个边缘的近边缘结构：(i) MoO 42- 和 MoS 42- 之间观察到的化学位移与线宽的比率，(ii) 近边缘结构分析的化学信息，以及 (iii) 使用荧光检测进行测量的难易程度。毫不奇怪，K 边是迄今为止最容易测量的，但它包含的信息最少。 L 2,3 -边缘虽然难以测量，但在选择规则和化学形态方面具有优势，因为它们具有更大的化学位移以及详细的线形，可以根据Mo配体场、对称性和共价性进行理论上分析。软X射线M 2,3 -边缘可能是最无用的，因为它们难以使用荧光检测来测量并且与相应的L 2,3 -边缘具有非常相似的信息内容。有趣的是，可以制作软 X 射线、低能量 (~230 eV) 边缘。这项工作包括四硫代钼酸钠的晶体学表征。
We have surveyed the chemical utility of the near-edge structure of molybdenum x-ray absorption edges from the hard x-ray K-edge at 20,000 eV down to the soft x-ray M 4,5 -edges at ~230 eV. We compared, for each edge, the spectra of two tetrahedral anions, MoO 4 and MoS 42- . We used three criteria for assessing near-edge structure of each edge: (i) the ratio of the observed chemical shift between MoO 42- and MoS 42- and the linewidth, (ii) the chemical information from analysis of the near-edge structure and (iii) the ease of measurement using fluorescence detection. Not surprisingly, the K-edge was by far the easiest to measure, but it contained the least information. The L 2,3 -edges, although harder to measure, had benefits with regard to selection rules and chemical speciation in that they had both a greater chemical shift as well as detailed lineshapes which could be theoretically analyzed in terms of Mo ligand field, symmetry, and covalency. The soft x-ray M 2,3 -edges were perhaps the least useful, in that they were difficult to measure using fluorescence detection and had very similar information content to the corresponding L 2,3 -edges. Interestingly, the soft x-ray, low energy (~230 eV) edges can be made. This work includes crystallographic characterization of sodium tetrathiomolybdate.