High spatial resolution analysis of H2O in silicate glass using attenuated total reflection FTIR spectroscopy coupled with a focal plane array detector
High spatial resolution analysis of H2O in silicate glass using attenuated total reflection FTIR spectroscopy coupled with a focal plane array detector
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DOI：
10.1016/j.chemgeo.2020.119833
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发表时间：
2020-12-05
期刊：
影响因子：
3.9
通讯作者：
Nowak, Marcus
中科院分区：
文献类型：
--
作者：
Allabar, Anja;Nowak, Marcus
用于确定地质玻璃中挥发性浓度的高分辨率光谱技术在确定小规模脱气或水合过程方面走在了前列。为此使用了几种光谱方法，但它们大多需要复杂的样品制备。在这里，通过使用衰减全反射(ATR)FTIR光谱和焦平面阵列探测器(FPA)来扩展这些方法。ATR-FTIR光谱只需要单一抛光的样品。与FPA探测器的耦合可以实现微米级的空间分辨率，这是分析挥发性轴承玻璃的新方法。提出了一种ATR-FPA定标方法来定量测定过碱性流纹岩玻璃中的H2O浓度，这与传统的使用单元素探测器的ATR定标方法具有可比性。结果证实，在根据先前的研究建议对玻璃密度进行校正后，不同玻璃成分的校准具有可比性。开发了一种方法来比较具有不同入射角的ATR物镜的定标结果。尽管使用FPA探测器会带来较大的误差，但该方法允许在微米尺度上检测H2O浓度梯度。ATR-FPA校准被应用于实验中冷却到玻璃的泡状熔体。在恒压冷却过程中形成的囊泡周围，只有几个微米大小的H2O吸收晕是可能的。除了泡状玻璃外，新方法还可以分析微小的熔融包裹体和部分结晶的玻璃，并可以对溶解在硅酸盐玻璃中的二氧化碳进行空间分辨分析。
High resolution spectroscopic techniques that are used to determine volatile concentration in geological glasses are on the forefront for determining small scale degassing or hydration processes. Several spectroscopic methods are used for this purpose but they mostly require complicated sample preparation. Here, these methods are extended by the use of attenuated total reflectance (ATR) FTIR spectroscopy coupled with a focal plane array detector (FPA). ATR-FTIR spectroscopy requires only singly polished samples. The coupling to an FPA detector, which is novel for the analysis of volatile bearing glasses, enables spatial resolution on a micrometer scale. An ATR-FPA calibration to quantify H2O concentration in peralkaline rhyolitic glass is presented, which is comparable to conventional ATR calibrations using a single element detector. The results confirm that calibrations for different glass compositions are comparable after correction for glass density as suggested by a previous study. A method is developed to compare calibrations obtained with ATR objectives that have different angles of incidence. Despite the larger errors that come with the use of an FPA detector, the method allows the detection of H2O concentration gradients on a micrometer scale.The ATR-FPA calibration was applied to experimentally vesiculated melts that were quenched to glasses. It was possible to resolve only several mu m-sized H2O resorption halos around vesicles that formed during isobaric cooling. Besides vesiculated glasses, the new method may enable the analysis of small melt inclusions and partially crystallized glasses and may allow the spatially resolved analysis of CO2 dissolved in silicate glasses.