Crystals of pyroxene are common in meteorites but few compositions have been recognized in astronomical environments due to the limited chemistries included in laboratory studies. We present quantitative room-temperature spectra of 17 Mg-, Fe-, and Ca-bearing ortho- and clinopyroxenes, and a Ca-pyroxenoid in order to discern trends indicative of crystal structure and a wide range of composition. Data are produced using a diamond anvil cell: our band strengths are up to six times higher than those measured in KBr or polyethylene dispersions, which include variations in path length (from grain size) and surface reflections that are not addressed in data processing. Pyroxenes have varied spectra: only two bands, at 10.22 and 15.34 μm in enstatite (En99), are common to all. Peak wavelengths generally increase as Mg is replaced by Ca or Fe. However, two bands in MgFe-pyroxenes shift to shorter wavelengths as the Fe component increases from 0 to 60 per cent. A high-intensity band shifts from 11.6 to 11.2 μm and remains at 11.2 μm as Fe increases to 100 per cent; it resembles an astronomical feature normally identified with olivine or forsterite. The distinctive pyroxene bands between 13 and 16 μm show promise for their identification in Mid-Infrared-Instrumentspectra obtained with the James Webb Space Telescope. The many pyroxene bands between 40 and 80 μm could be diagnositic of silicate mineralogy if data were obtained with the proposed Space Infrared Telescope for Cosmology and Astrophysics. Our data indicate that comparison between room-temperature laboratory bands for enstatite and cold ∼10 − K astronomical dust features at wavelengths ≳28 μm can result in the identification of (Mg,Fe)- pyroxenes that contain 7–15 per cent less Fe– than their true values because some temperature shifts mimic some compositional shifts. Therefore some astronomical silicates may contain more Fe, and less Mg, than previously thought.

中文翻译：

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辉石（结晶链硅酸盐）在室温下的红外光谱

辉石晶体在陨石中很常见，但由于实验室研究中包含的化学成分有限，在天文环境中很少有成分被发现。我们提供了 17 种含 Mg、Fe 和 Ca 的邻辉石和单斜辉石以及 Ca 辉石的定量室温光谱，以辨别指示晶体结构和广泛组成范围的趋势。数据是使用金刚石砧座生成的：我们的能带强度比在 KBr 或聚乙烯分散体中测量的强度高六倍，其中包括路径长度的变化（来自晶粒尺寸）和数据处理中未解决的表面反射。辉石具有不同的光谱：在顽火辉石 (En99) 中只有 10.22 和 15.34 μm 的两个谱带是通用的。随着 Mg 被 Ca 或 Fe 取代，峰值波长通常会增加。然而，当 Fe 成分从 0% 增加到 60% 时，MgFe-辉石中的两个波段移向更短的波长。当 Fe 增加到 100% 时，高强度带从 11.6 μm 移动到 11.2 μm 并保持在 11.2 μm；它类似于通常以橄榄石或镁橄榄石识别的天文特征。13 到 16 μm 之间的独特辉石带显示出在使用詹姆斯韦伯太空望远镜获得的中红外仪器光谱中对其进行识别的希望。如果使用拟议的宇宙学和天体物理学空间红外望远镜获得数据，那么 40 到 80 微米之间的许多辉石带可以诊断硅酸盐矿物学。我们的数据表明，对比顽火石和冷~10-K 天文尘埃特征在波长 ≳28 μm 的室温实验室波段之间的比较，可以识别 (Mg, Fe)-辉石的铁含量比它们的真实值少 7-15%，因为一些温度变化模仿了一些成分变化。因此，一些天文硅酸盐可能含有比以前认为的更多的铁和更少的镁。