Neutron reflectometry for the invesgation of multilayer coatings for building applications

Neutron reflectometry is a very useful and powerful surface analysis technique for the investigation of fenestration coated glass. The collimated neutron beam with variable wavelength of the EROS G3-bis time-of-flight spectrometer of Laboratoire Leon Brillouin, CEA-Saclay, France, impinges on the flat surface of an air coating substrate system at grazing angle and the neutron reflectance spectrum is recorded. The structure of the analysed coating is then obtained from this spectrum (with the help of at least one complementary technique in the case of a multilayer coating) and by applying the classical Fresnel laws of reflections. Neutron reflectometry has been extensively used by the authors for evaluating thickness and density of thin films of different materials deposited on flat glass as single or multilayers. This technique also allows the evaluation of the roughness between adjacent layers (including the air/coating and the coating/substrate interfaces). The main goal of the paper is the preparation of a database containing the density of the materials composing the single and multilayers produced by the industry on flat glass for building applications.