Selective transport of light vs. heavy rare earth elements by sulfate/bisulfate complexes in hydrothermal fluids

The speciation of Nd (light REE) and Yb (heavy REE) sulfate complexes were determined via in situ Raman spectroscopy using fused SiO2 capillary cells up to 300 ºC at saturated water vapor pressure and in a hydrothermal diamond anvil cell up to 500 ºC and 540 MPa. Table S1 contains experimental solution compositions, temperature, pressure, fitted Lorentzian Raman peak positions, peak areas, and calculated molalities for the various experiments. Table S2 contains the compiled processed sulfate and bisulfate region spectra for all experiments. Table S3 contains compiled processed water band region spectra for all experiments. Processing involves an instrument-specific correction, frequency and scattering correction for laser wavelength, the Bose-Einstein factor for temperature, and baseline subtraction. See SI Section 1 of the article for spectral correction methods.

本研究通过原位拉曼光谱法开展实验，分别采用熔融石英（fused SiO₂）毛细管池（实验条件为饱和水蒸气压力，最高温度达300 ℃）与热液金刚石压腔（hydrothermal diamond anvil cell，最高实验温度500 ℃、压力540 MPa），测定了钕（Nd，轻稀土元素（light rare earth element））与镱（Yb，重稀土元素（heavy rare earth element））的硫酸盐配合物形态赋存状态。附表S1收录了各实验组的实验溶液组成、温度、压力、拟合得到的洛伦兹型（Lorentzian）拉曼峰位、峰面积以及计算得到的质量摩尔浓度。附表S2收录了所有实验经整理与预处理的硫酸盐及硫酸氢盐特征波段光谱数据。附表S3收录了所有实验经整理与预处理的水特征波段光谱数据。上述光谱预处理流程包括仪器专属校正、激光波长对应的频率与散射校正、基于温度的玻色-爱因斯坦（Bose-Einstein）因子校正，以及基线扣除。光谱校正方法详见论文补充信息（SI）第1节。