Monte Carlo SEM-EDS micro- and nanoanalysis of ultrathin gold leaves in glass mosaic tesserae: Thickness effects and measurement strategy

Scanning Electron Microscopy (SEM) coupled to Energy Dispersive X-ray Spectrometry (EDS) is a very effective methodology to investigate the local composition of ultrathin materials, such as metal leaves in glass mosaic tesserae. However, a careful analytical strategy must be considered when dealing with this type of investigations, because the metal leaf is extremely thin, typically 0.2-1 μm. Many artefacts could arise from the electron and X-ray scattering in the thin metal leaf and adjacent glass layers and from EDS detector - sample configurations and arrangements. In this work, Monte Carlo simulation was used to study the effects related to the metal leaf thickness, tessera composition, SEM-EDS setup and detector physics, in order to understand the limits of the methodology. A general micro-nanoanalytical strategy for accurate SEM-EDS quantitative analysis is provided to the interested reader, also useful for other ultrathin layers, substrates, composites, powder materials and micro - nanosized specimens.