A combined theoretical and experimental investigation of the electronic and vibrational properties of red lead pigment

The electronic and vibrational properties of red lead pigment, the mixed valence lead oxide compoundPb3O4, known as minium, have been studied by means of first principle calculations based on DensityFunctional Theory (DFT) and Fourier Transform–Infra Red (FT-IR) and Raman spectroscopies. The aim ofthe present investigation is to validate an integrated theoretical-experimental approach for modellingthe structural, electronic and spectroscopic properties of minium and to define its structure-propertiesrelationships. The calculated band gap performed using GW approximation is in excellent agreementwith the experimental one and improves previous results found in literature. The simulated vibrationalIR and Raman spectra are able to reproduce the main features of the experimental spectra and to assignthe normal modes related to the experimental bands. The combined theoretical and experimental studyof the electronic and vibrational properties of Pb3O4allows to clarify the mechanism of lead whiteningas well as to interpret ambiguous Raman spectra of minium in terms of resonance effects.