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 compound PbO, known as minium, have been studied by means of first principle calculations based on Density Functional Theory (DFT) and Fourier Transform-Infra Red (FT-IR) and Raman spectroscopies. The aim of the present investigation is to validate an integrated theoretical-experimental approach for modelling the structural, electronic and spectroscopic properties of minium and to define its structure-properties relationships. The calculated band gap performed using GW approximation is in excellent agreement with the experimental one and improves previous results found in literature. The simulated vibrational IR and Raman spectra are able to reproduce the main features of the experimental spectra and to assign the normal modes related to the experimental bands. The combined theoretical and experimental study of the electronic and vibrational properties of PbO allows to clarify the mechanism of lead whitening as well as to interpret ambiguous Raman spectra of minium in terms of resonance effects.