Raman Spectroscopy of Siderite with q-Gaussian and split-q-Gaussian Analyses

In a previous review, ChemRxiv, 2023, we have considered the iron oxides and their related Raman spectra; in the review, fingerprints of Magnetite, Maghemite, Hematite, Goethite, Lepidocrocite, Akaganeite and Siderite have been given and the q-Gaussian fitting of some Magnetite, Hematite and Lepidocrocite Raman bands has been proposed too. Here we consider one of the Raman bands of Siderite and its fitted q-Gaussian and split-q-Gaussian functions in depth. In the RRUFF database six natural siderite samples are included, and for three of them we can find Raman spectra obtained with different excitation lasers. These spectra allow us to investigate in detail the behavior of the fitted q-Gaussian curves. A discussion about the origin of asymmetry is also proposed, relevant for the use of q-Gaussians and the interpretation of them in the framework of Kubo approach.