Water quantification in silicate glasses by Raman spectroscopy: Correcting for the effects of confocality, density and ferric iron
Water quantification in silicate glasses by Raman spectroscopy: Correcting for the effects of confocality, density and ferric iron
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通过拉曼光谱对硅酸盐玻璃中的水进行定量：校正共焦、密度和三价铁的影响
DOI：
10.1016/j.chemgeo.2018.02.036
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发表时间：
2018
期刊：
影响因子：
3.9
通讯作者：
A. Gómez
中科院分区：
文献类型：
--
作者：
F. Schiavi;N. Bolfan;A. Withers;E. Médard;M. Laumonier;D. Laporte;T. Flaherty;A. Gómez
新系列的铝硅酸盐玻璃跨越广泛的化学成分（玄武岩，拉斑玄武岩，钙碱性安山岩，过铝和过碱性流纹岩）和水含量从0.02至6.70重量%，用于改进的方法的定量溶解水与高共焦拉曼显微光谱仪。在重新考虑以前提出的光谱采集和分析后数据处理的方法后，我们定义了主要的关键步骤，使玻璃基体效应最小化。首先，我们仔细评估了拉曼谱带强度的变化，在水（~3000-3800 cm−1）和铝硅酸盐振动（~200-1250 cm−1）区域与样品内的激光束的焦点深度。结果表明，在2-10 μm深度范围内，铝硅酸盐区的强度增长是水区的2倍。最佳的聚焦深度，其中的水带的信号是最大的和水带的铝硅酸盐带的强度比是最小的，与玻璃组成和共焦性能的拉曼光谱仪而变化。这会影响外部和内部校准斜率。其次，本研究认识到与玻璃密度，三价铁和溶解碳酸盐的存在下，主要负责内部校准方法的基质效应的关键参数。(a)我们提供了一个程序，用于校正玻璃密度对水内部校准的影响的基础上观察到的铝硅酸盐信封的积分强度（即面积）一般下降，随着水含量的增加和玻璃密度的降低。(b)在含CO2的玻璃中，在应用密度校正之前，必须从铝硅酸盐包络的强度中减去溶解的碳酸盐在~1087 cm− 1处的ν 1拉曼振动的强度。(c)使用峰值拟合，过碱性流纹岩玻璃的850-1250 cm− 1包络线的强度被校正为存在四重配位的Fe 3+的影响，正如在~980 cm−1处振动模式的强拉曼散射所揭示的那样。按照这个程序，所有研究的玻璃定义一个单一的校准线，尽管其组成的变化，当使用两个经典的方法称为externalandinternalcalibration方法。外部和内部校准的线性拟合分别在0.13-0.11重量%（高和标准共焦性）和0.17重量%内再现整个数据集。通过与离子探针法测量天然玻璃包裹体中溶解水的结果比较，评价了外定标的准确性：平均相对标准偏差为~4%（1σ），当水含量为~ 0.1wt%时，相对标准偏差可达~12%（1σ）。
New series of alumino-silicate glasses spanning a wide range of chemical compositions (basanites, tholeiitic basalts, calcalkaline andesites, peraluminous and peralkaline rhyolites) and with water contents from 0.02 to 6.70 wt% were used for improving the method of quantification of dissolved water with a highly confocal Raman micro-spectrometer. After reconsideration of previously proposed methods for spectra acquisition and post-analysis data treatment, we define the main critical steps that allow minimizing glass matrix effects. First, we carefully assess the variation of Raman band intensities, in both water (~3000–3800 cm−1) and alumino-silicate vibration (~200–1250 cm−1) regions with focus depth of the laser beam inside the sample. Our results indicate that in the first 2–10 μm depth, the intensity increase in the alumino-silicate region is twice as high as that in the water region. Optimal focus depths, where the signal of the water band is maximum and the intensity ratio of the water band to alumino-silicate band is minimum, vary with glass composition and confocal performance of the Raman spectrometer. This influences both external and internal calibration slopes. Second, this study recognizes critical parameters related with glass density, presence of ferric iron and dissolved carbonates as mainly responsible for matrix effects on the internal calibration method. (a) We provide a procedure for correcting the effect of glass density on water internal calibration based on the observation that the integrated intensity (i.e. the area) of the alumino-silicate envelope generally drops with the increase of water content and decrease of glass density. (b) In CO2-bearing glasses, the intensity of theν1Raman vibration of dissolved carbonate at ~1087 cm−1has to be subtracted from the intensity of the alumino-silicate envelope before applying the density correction. (c) Using peak-fitting, the intensity of the 850–1250 cm−1envelope of peralkaline rhyolitic glasses is corrected for the effect of the presence of four-fold coordinated Fe3+, as revealed by the strong Raman scattering of the vibrational mode at ~980 cm−1. Following this procedure, all the studied glasses define a single calibration line in spite of their compositional variability, when using either of the two classical approaches referred to asexternalandinternalcalibration methods. The linear fits of the external and internal calibrations reproduce the whole dataset within 0.13–0.11 wt% (high and standard confocality) and 0.17 wt%, respectively. The accuracy of the external calibration is evaluated based upon comparison with ion-probe measurements of water dissolved in natural glass inclusions: the relative standard deviation is ~4% (1σ) on average, and reaches ~12% (1σ) for water contents of ~0.1 wt%.
影响因子：
3.9
作者：
Di Genova, Danilo;Sicola, Stefania;Spina, Laura
通讯作者：
Spina, Laura
成分和压力对镁铁质熔体中 H2O 和 CO2 溶解度的影响
影响因子：
3.9
作者：
Shishkina T.A;Botcharnikov R.E;Holtz F;Almeev R;Jazwa A;Jakubiak A.
通讯作者：
Jakubiak A.