Quantification of dissolved H2O in silicate glasses using confocal microRaman spectroscopy
Quantification of dissolved H2O in silicate glasses using confocal microRaman spectroscopy
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DOI：
10.1016/j.chemgeo.2006.01.014
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发表时间：
2006-05-16
期刊：
影响因子：
3.9
通讯作者：
Siemann, Michael
中科院分区：
文献类型：
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作者：
Behrens, Harald;Roux, Jacques;Siemann, Michael
应用共焦显微拉曼光谱的总水含量和水形态的定量进行了测试，含水玻璃的各种组合物（单花岗岩，钠长石，英云闪长岩，过碱性流纹岩，英安岩，安山岩，玄武岩）。水含量在0.5和11重量%之间的玻璃在内部加热的气体压力容器中合成。通过卡尔-费歇尔滴定法和红外光谱法测量玻璃的总水含量。为了通过拉曼光谱定量总含水量（CH 2 Ot），直接使用3550 cm（-1）处OH伸缩振动带的积分强度（A（3550）（*））或将A（3550）（*）缩放至低波数拉曼带。一个非常高的再现性A 3550可以实现与一个独立的拉曼显微镜LabRam 010。单个回归线再现了所有样品的数据，2 σ变化为1.2重量%。然而，在A（3550）（*）与水含量的曲线图中，观察到聚合组合物（单斜花岗岩、钠长石、英云闪长岩）、中间组合物（英安岩、安山岩）和解聚组合物（玄武岩）的趋势略有不同，这意味着溶解的含水物质的拉曼截面取决于玻璃组合物。在使用拉曼光谱仪T64000进行测量时，A（3550）（*）在很大程度上取决于测量条件。只有用低波数谱带对OH谱带强度进行归一化，才能获得良好的重现性。这种方法具有至少部分地消除特定测量条件的影响的优点，并且因此打开了将拉曼校准应用于另一光谱仪的可能性。对于反射镜玻璃，缩放到接近500 cm（-1）（A（500）（*））的T-O-T弯曲带的面积产生最佳结果。钠长石、单斜花岗岩和英安岩的数据（11个样品，37个光谱），覆盖0.8-7.3重量%的范围H2O的2 σ标准偏差为0.16重量% H2O by CH2Ot（wt.%）= 3.66（.）A（3550）（*）/A（500）（*）对于中间和解聚的组合物，1000 cm（-1）附近的T-O伸缩带比500 cm（-1）附近的T-O-T弯曲带更强，因此，它更便于校准。安山岩和玄武岩的数据（14个样品，22个光谱），覆盖0.5至4.7重量%的范围H2O的2 σ标准偏差为0.18重量% H2O by CH2Ot（wt.%）= 3.66（.）A（3550）（*）/A（1000）（*）通过将OH伸缩拉曼谱带分解为3-5高斯谱带来确定玻璃中OH基团和H2O分子的相对丰度的尝试与来自近红外光谱的水形态数据不一致。
Application of confocal microRaman spectroscopy for quantification of total water content and water speciation was tested for hydrous glasses of various compositions (haplogranite, albite, tonalite, peralkaline rhyolite, dacite, andesite, basalt). Glasses with water contents between 0.5 and 11 wt.% were synthesized in internally heated gas pressure vessels. Total water contents of the glasses were measured by Karl-Fischer titration and IR spectroscopy. To quantify the total water content (CH2Ot) by Raman spectroscopy either the integrated intensity of the OH stretching vibration band at 3550 cm(-1) (A(3550)(*)) was used directly or A(3550)(*) was scaled to low wavenumber Raman bands. A very high reproducibility Of A 3550 could be achieved with a stand alone Raman microscope LabRam 010. A single regression line reproduces the data of all samples with a 2 sigma variation of 1.2 wt.%. However, slightly different trends are observed for polymerized compositions (haplogranite, albite, tonalite), intermediate compositions (dacite, andesite) and depolymerized compositions (basalt) in Plots Of A(3550)(*) VS. water content, implying that the Raman cross section of dissolved hydrous species depends on glass composition. In measurements with a Raman spectrometer T64000, A(3550)(*) depends largely on measurement conditions. A good reproducibility could be achieved only by normalizing the OH band intensity with low wavenumber bands. Such an approach has the advantage to eliminate at least partially effects of specific measurement conditions and, hence, opening the possibility to apply the Raman calibration to another spectrometer. For silicic glasses scaling to the area of T-O-T bending band near 500 cm(-1) (A(500)(*)) yields the best results. Data for albite, haplogranite and dacite (11 samples, 37 spectra) covering a range of 0.8-7.3 wt.% H2O are reproduced with a 2 sigma standard deviation of 0.16 wt.% H2O byCH2Ot (wt.%) = 3.66 (.) A(3550)(*)/A(500)(*)For intermediate and depolymerized compositions the T-O stretching band near 1000 cm(-1) is more intensive than the T-O-T bending band near 500 cm(-1) and, hence, it is more convenient for calibration. Data for andesite and basalt (14 samples, 22 spectra) covering a range of 0.5 to 4.7 wt.% H2O are reproduced with a 2 sigma stand deviation of 0.18 wt.% H2O byCH2Ot (wt.%) = 3.66 (.) A(3550)(*)/A(1000)(*)Attempts to determine the relative abundance of OH groups and H2O molecules in the glasses by decomposing the OH stretching Raman band into 3-5 Gaussians are not consistent with water speciation data derived from near-infrared spectroscopy.