European XFEL is an international non-profit company located in the Hamburg area in Germany. It operates a 3.4 km-long X-ray laser, which produces X-rays of unique quality for studies in physics, chemistry, the life sciences, materials research and other disciplines. The diverse scientific facilities at European XFEL enable scientists from across the globe to carry out a wide range of experimental techniques. The FXE (Femtosecond X-ray Experiments) scientific instrument at the European XFEL embraces several fields of ultrafast X-ray science and their applications by ultrafast pump–probe experiments on timescales below 100 femtoseconds. Within the scope of a recently approved R&D project about ultrafast X-ray a