Ultrahigh-Energy-Resolution Inelastic X-Ray ScatteringSpectroscopy

Very-high-energy-resolution measurements using X-rays can be achieved by extreme backreflection(Bragg angle close to 90°) from perfect crystals. This technique allowed the development of theinstrument INELAX for inelastic scattering experiments at the HARWI wiggler at DORIS, DESYHamburg. Recently, a high energy resolution of 9 meV could be achieved, and the instrument provedto be an excellent tool to investigate collective excitations in condensed matter. Energy transfersfrom 10 meV to 12 eV and wave vectors up to about 10 Ä - 1 are accessible