Measurement of Transient Photo-induced Changes in Thin Films at J-PARC – Time-resolved Neutron Reflectivity Measurements of Silver Photo-diffusion into Ge-chalcogenide Films

Study on photo-induced changes for specific light-sensitive materials is fascinating from both academic and application points of view because it is one of the frontiers in materials science including concepts of electron-excitation and non-equilibrium state, and the materials can be controlled spatially by illuminated area from distant place [1]. With the aid of significant development of light source equipment such as femtosecond ultra-short pulsed laser systems, attractive photo-induced phenomena have been found in many materials in these days. In the leading-edge field, it is quite natural to be interested in finding the structural origin of the photo-induced changes. Although neutron scattering technique has always a difficulty in beam intensity, it is highly expected to be utilized in structural determination for magnetic materials, hydrogenated materials, and X-ray sensitive materials. At the Materials and Life Science Experimental Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC), the proton beam intensity is now 300kW, and it is planned to go to 1MW in