Novel application of silicon multi-vacancy satellite peaks for silicate minerals analysis in igneous rocks using WD-XRF coupled with chemometrics analysis†

X-ray spectra are pivotal for understanding chemical bonding and atomic interactions in materials. Particularly, valence-to-core (VtC) electronic transitions and satellite peaks within X-ray spectra provide insights into valence states and chemical environments. This study focuses on the multi-vacancy satellite peaks, Si Kβ^III and Kβ^IV, and their application in analyzing silicate minerals in igneous rocks. A wavelength dispersive X-ray fluorescence (WD-XRF) spectrometer, commonly employed for chemical analysis of geological samples, was utilized in this study. The Si Kβ^III and Kβ^IV peaks were selected due to their VtC transitions and multi-vacancy origin, offering enhanced sensitivity to the chemical environment. We examined 41 certified reference materials (CRMs) of igneous rocks, demonstrating the capability of these satellite peaks to reveal detailed chemical and structural information. A strong correlation was found between the chemical composition of silicate minerals and the intensities along with chemical shifts of the Si Kβ^III and Kβ^IV peaks. We developed a regression model to predict mineral concentrations, validating the method with CRMs. The results suggest that the spectral region of the Si Kβ^III and Kβ^IV peaks serves as a distinctive fingerprint for identifying silicate minerals in igneous rocks.