The Emu backscattering spectrometer at the Australian Centre for Neutron Scattering (OPAL reactor, ANSTO) provides high-resolution neutron spectroscopy for investigating atomic and molecular relaxation processes over correlation times ranging from tens of picoseconds to several nanoseconds [1]. With an energy resolution of 1 µeV, an energy transfer range of ±31 µeV, and a momentum-transfer range of 0.2–1.95 Å⁻¹, Emu is particularly well suited for quasi-elastic neutron scattering (QENS) experiments. Its high sensitivity to hydrogen makes it especially powerful for studying organic and hydrogen-rich materials and enables detailed characterization of slow molecular processes in polymers, membranes, proteins, and molecular crystals.
We present studies of polymer dynamics that illustrate Emu’s capabilities. Using QENS, we investigate both bottlebrush polymers and alternating polymer electrolytes. In bottlebrush polymers, slow segmental relaxation and local methyl-group dynamics are resolved. Methyl-group rotations are geometrically confined and can be described by a modified threefold jump model, demonstrating how molecular architecture influences macroscopic properties such as softness and viscosity [2, 3].
In alternating polymer electrolytes, QENS reveals heterogeneous segmental dynamics in which fast polymer segments act as internal plasticizers while slower segments host Li⁺ ions [4]. This dynamic asymmetry correlates with enhanced ionic conductivity, illustrating how molecular-scale motions govern macroscopic transport properties.
Emu operates over a wide temperature range from 50 mK to 800 K and is supported by ancillary capabilities including controlled gas environments, pressure cells, and magnetic-field sample environments. Through merit-based access, Emu serves a global user community studying relaxation phenomena in soft condensed matter physics, materials science, and biophysics, enabling direct connections between microscopic dynamics and functional material properties.