Combining photo- and magneto-strictive properties in epitaxial heterostructures provides a versatile approach to optically control magnetic properties through a strain-mediated mechanism. However, a screening of the parameters which govern the mechanical coupling is still required to optimize the response of these heterointerfaces. During this preparation stage, we plan to optimize kinetic measurements on two samples made of Prussian blue analogues and quantify the time scale of the photo-excitation under X-ray irradiation on (1) single-phase photoactive particles (140 nm size) and (2) a core-shell particle sample (170 nm size). No laser will be used for these test experiments. The samples will be directly photo-excited by the incident x-rays.