Abstract
We measured nuclear forward scattering spectra utilizing the Ru99 transition, 89.571(3) keV, with a notably mixed E2/M1 multipolarity. The extension of the standard evaluation routines to include mixed multipolarity allows us to extract electric and magnetic hyperfine interactions from Ru99-containing compounds. This paves the way for several other high-energy Mössbauer transitions, E∼90 keV. The high energy of such transitions allows for operando nuclear forward scattering studies in real devices.