Effects of small crystallite size on the thermal infrared (vibrational) spectra of minerals
Effects of small crystallite size on the thermal infrared (vibrational) spectra of minerals
复制标题
小晶粒尺寸对矿物热红外（振动）光谱的影响
DOI：
10.2138/am-2020-7602
复制
发表时间：
2020
影响因子：
3.1
通讯作者：
T. Mayerhöfer
中科院分区：
文献类型：
--
作者：
V. Hamilton;C. Haberle;T. Mayerhöfer
摘要一组人工合成的镁铁橄榄石的热红外（TIR，或振动）发射光谱在带形、相对深度和某些带位的移动与天然火成岩对应物有显著差异。从橄榄石为主的矩阵和熔融壳的一些碳质球粒陨石获得的反射率光谱表现出类似的偏差。在这里，我们表明，这些不寻常的光谱特性是一致的微晶尺寸远小于红外光的分辨率极限。我们推测，这些小微晶表示缩短晶体生长，也可能与成核位点的大小。其他硅酸盐和非硅酸盐，如碳酸盐，表现出类似的光谱行为。由于矿物分离物的光谱通常用于可比的大块岩石、陨石和遥感数据的建模和分析，因此理解这些光谱变化对于正确识别矿物和解释天然材料的起源和/或二次加工历史是重要的。
Abstract The thermal infrared (TIR, or vibrational) emission spectra of a suite of synthetic Mg-Fe olivines exhibit notable differences from their natural igneous counterparts in terms of their band shapes, relative depths, and reduced shifts in some band positions with Mg-Fe solid solution. Comparable reflectance spectra acquired from olivine-dominated matrices and fusion crusts of some carbonaceous chondrite meteorites exhibit similar deviations. Here we show that these unusual spectral characteristics are consistent with crystallite sizes much smaller than the resolution limit of infrared light. We hypothesize that these small crystallites denote abbreviated crystal growth and also may be linked to the size of nucleation sites. Other silicates and non-silicates, such as carbonates, exhibit similar spectral behaviors. Because the spectra of mineral separates are commonly used in the modeling and analysis of comparable bulk rock, meteorite, and remote sensing data, understanding these spectral variations is important to correctly identifying the minerals and interpreting the origin and/or secondary processing histories of natural materials.