Simulation of PIXE-induced XRF spectra for characterizing iron-containing compounds in aerosol using Fe Lα

Simulation to reproduce the fine structure of Fe Lα in PIXE-induced XRF spectra has been successfully performed using XRF spectra. Fe Lα XRF spectra emitted from Fe, α-Fe2O3, Fe3O4 and FeSO4, i.e. Fe-containing compounds expected in aerosols, split into two components and have different shapes characteristic of these compounds. Such splitting is explained here in view of the molecular orbital scheme. The Lα X-rays originating from the occupied molecular orbitals including, at least in part, Fe 3d orbitals of the atom of interest, are absorbed by neighboring Fe atoms where a part of the emitted X-rays are used to excite Fe 2p electrons to the unoccupied molecular orbitals composed of Fe 3d. This suggests that the chemical species of a very small amount of Fe-containing aerosols are expected to be distinguished using Fe L emission spectra which are induced by the PIXE-induced XRF method.