Abstract We analyzed plagioclase feldspar samples that were well-characterized in terms of chemical composition as well as degree of Al,Si order in mid-infrared reflection spectra between 7 μm and 14 μm (1429 cm−1 and 714 cm−1). The chemical compositions were derived with an electron microprobe analyzer. To determine the degree of Al,Si order, powder X-ray diffraction methods were applied. For the interpretation of the infrared spectra, we used the wavelength of the Christiansen feature (CF) and the autocorrelation function for a specific wavelength region. The CF shifts from around 7.72 μm (1296 cm−1) in Na-richest samples to 8.10 μm (1234 cm−1) in the Ca-richest sample. Combining the CF position and the autocorrelation-derived value allowed to determine the degree of Al,Si order of the samples based on reflection spectra. The wavelength of the Transparency feature (TF) in the finest analyzed grain size fraction also depends on the chemical composition and the degree of Al,Si order. Our results are helpful for the interpretation of data returned by the MERTIS experiment onboard BepiColombo. The data help to distinguish between space weathering, shock effects, and ordering effects in plagioclase samples.

中文翻译：

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具有各种 Al、Si 阶次的结晶斜长石样品的中红外光谱及其对水星和其他地球太阳系天体遥感的影响

摘要 我们分析了斜长石样品，这些样品在 7 μm 和 14 μm（1429 cm-1 和 714 cm-1）之间的中红外反射光谱中的化学成分和 Al、Si 有序度方面得到了很好的表征。化学成分是用电子探针分析仪得出的。为了确定铝、硅的有序度，应用了粉末 X 射线衍射方法。对于红外光谱的解释，我们使用了 Christiansen 特征 (CF) 的波长和特定波长区域的自相关函数。CF 从 Na 含量最高的样品中的约 7.72 μm (1296 cm-1) 转变为 Ca 含量最高的样品中的 8.10 μm (1234 cm-1)。结合 CF 位置和自相关导出值，可以根据反射光谱确定样品的 Al、Si 阶数。最细分析晶粒尺寸部分的透明特征 (TF) 的波长还取决于化学成分和 Al、Si 的有序程度。我们的结果有助于解释 BepiColombo 上 MERTIS 实验返回的数据。这些数据有助于区分斜长石样品中的空间风化、冲击效应和排序效应。