DiadFit: An open-source Python3 tool for peak fitting of Raman data from silicate melts and CO2 fluids

Abstract

We present DiadFit—an open-source Python3 tool for efficient processing of Raman spectroscopy data collected from fluid inclusions, melt inclusions and silicate melts. DiadFit is optimized to fit the characteristic peaks from CO₂ fluids (Fermi diads, hot bands, ¹³C), gas species such as SO₂, N₂, solid precipitates (e.g. carbonates), and Ne emission lines with easily tweakable background positions and peak shapes. DiadFit's peak fitting functions are used as part of a number of workflows optimized for quantification of CO₂ in melt inclusion vapour bubbles and fluid inclusions. DiadFit can also convert between temperature, pressure and density using various CO₂ and CO₂-H₂O equations of state (EOS), allowing calculation of fluid inclusion pressures (and depths in the crust), conversion of homogenization temperatures from microthermometry to CO₂ density, and propagation of uncertainties associated with EOS calculations using Monte Carlo methods. There are also functions to quantify the area ratio of the silicate vs. H₂O region of spectra collected on silicate glasses to determine H₂O contents in glasses and melt inclusions. Documentation and worked examples are available (https://bit.ly/DiadFitRTD, https://bit.ly/DiadFitYouTube).