Multi-pulse laser irradiation of cadmium yellow paint films: The influence of binding medium and particle aggregates

The present work is focused on the study of laser-induced effects that can occur in cadmium yellow paint films. To this aim, samples were prepared with different binders (linseed oil and polyvinylalcohol), mixing methods (manual vs. sonication) and pigment volume concentration (PVC). Laser experiments were performed under a microscope-based setup coupled to a spectrometer, which allowed to study surface and in-depth changes thanks to 2D image processing and 3D reconstructions. The present methodology revealed effective for studying the role that binder, particle-size and density distribution have upon laser irradiation. Results showed the threshold fluences strictly depend on the type of binder and PVC. The damage nucleation is size-dependent with fluence and PVC, and the micro-damaged sites can be ascribed to non-linear absorption of CdS aggregates, whose size is of the order of the incident wavelength. These conclusions were further corroborated by Vis-NIR PL emission and reflection and ESEM-EDX.