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.