Fastosh: a software for the treatment of XAFS datasets of environmental relevance or acquired in operando conditions.

Fastosh is a freeware dedicated to the treatment of X-ray absorption fine-structure (XAFS) spectroscopy data. The program features functions that are particularly suitable for geochemical and environmental applications and treatment of XAFS datasets acquired in operando conditions. It can be employed to identify the nature of chemical species present as principal components in a sample mixture, which is a case commonly encountered when studying a set of natural samples or a chemical reaction followed in situ at the beamline, where multiple species may coexist, including intermediary species. Additionally, the software features unique functionalities that notably allow to filter in two dimensions and plot in three dimensions time-dependent datasets; rapidly deglitch chi spectra; automatically view in 2D or 3D and merge XAFS data acquired at the beamline; and visualize an EXAFS wavelet transform map as well as interpret it and its associated chi and Fourier transform spectra using a quick modelling approach where theoretical single scattering paths are employed. All these functions can be applied to XAFS data generated in ASCII format at any XAFS beamlines. Lastly, the program specifically allows users of SAMBA beamline, Synchrotron SOLEIL, to easily access all contextual data associated with an XAFS acquisition or process the raw data collected by the multi-pixel fluorescence detector of the beamline, which are saved in an HDF file. The structure of this file, and all related functions in Fastosh to exploit it, could be readily adapted to comply with a universal HDF format, which hopefully will be defined and adopted in the future by multiple XAFS beamlines worldwide.