Determination of molar absorptivity of IR fundamental OH-stretching vibration in rhyolitic glasses
Determination of molar absorptivity of IR fundamental OH-stretching vibration in rhyolitic glasses
复制标题
流纹岩玻璃中红外基本 OH 伸缩振动摩尔吸收率的测定
DOI：
10.2138/am-2003-11-1204
复制
发表时间：
2003
影响因子：
3.1
通讯作者：
S. Nakashima
中科院分区：
文献类型：
--
作者：
S. Okumura;M. Nakamura;S. Nakashima
摘要测定了流纹质玻璃在3550 cm-1处红外OH伸缩振动带的摩尔吸收系数。使用未加热和使用内部加热压力容器在500-700 °C下加热的五个黑曜石样品来评估摩尔吸光系数和最终淬灭的H2O形态对H2O含量和温度的依赖性。采用卡尔-费休滴定法测定黑曜岩样品的含水量，然后用红外光谱法和真空萃取法对样品中未萃取的水进行校正。测定黑曜岩的总H2O含量为0.24-1.25重量%。使用FT-IR显微光谱仪获得了未加热和加热的黑曜石样品的IR光谱。我们测定了3550 cm-1带的摩尔吸光系数为75 ± 4 L/mol/cm，与H2O含量和加热温度无显著依赖性。该值可用于测定流纹质火山玻璃中高达1.25wt%的精确H2O含量。
Abstract Molar absorptivity of the infrared (IR) fundamental OH-stretching vibration band at 3550 cm-1 was determined for rhyolitic glasses. Five obsidian samples, unheated and heated at 500-700 °C using an internally heated pressure vessel, were used to evaluate the dependence of the molar absorptivity and final quenched H2O speciation on H2O contents and temperature. Water contents of the obsidians were measured by Karl-Fischer titration first, then the amount of unextracted H2O was calibrated by IR spectroscopy and a conventional vacuum extraction method. Total H2O contents of the obsidians were determined to be 0.24-1.25 wt%. IR spectra of the unheated and heated obsidian samples were obtained using an FT-IR microspectrometer. We determined the molar absorptivity for the 3550 cm-1 band to be 75 ± 4 L/mol/cm without significant dependence on the H2O contents and heating temperature. This value can be used to determine precise H2O contents up to 1.25 wt% in rhyolitic volcanic glasses.