Sample environment for simultaneous quasi-elastic neutron scattering and Raman spectroscopy experiments demonstrated on polymer films under changing humidity and temperature

Understanding the dynamic and structural properties of matter across different timescales and length scales is essential for elucidating their functionality. We focus here on soft-matter systems, which are typically particularly sensitive to relative humidity (RH) and temperature, necessitating well controlled experimental conditions. Quasi-elastic neutron scattering (QENS) and Raman spectroscopy offer complementary insights: QENS accesses diffusional dynamics, which are stochastic motions, while Raman spectroscopy provides information on periodic vibrational dynamics. To enable simultaneous QENS and Raman measurements on <i>e.g.</i> polymer films under controlled and variable RH and temperature, we have developed a dedicated sample environment (SE), which in the presented experiments covers an RH range of 5-85% and a temperature range of 20-50°C. This SE features a 3D-printed spherical chamber including a sample holder for films, a Raman spectrometer, a custom-built gas-flow system and a thermostat. The chamber can accommodate large samples (up to 5 × 5 cm) and provides space for additional measurement equipment. The 3D-printing technique allows the integration of channels into the chamber walls, which are used for cooling and heating, resulting in highly homogeneous temperature distributions. This is key to achieving a uniform humidity in the chamber. The chamber works with a variety of solvents and their mixtures, like heavy water or ethanol. We demonstrate the feasibility of this setup through simultaneous QENS and Raman measurements on poly(3,4-ethylene di-oxy-thio-phene):poly(styrene-sulfonate) films on Si substrates, confirming that the chamber provides a stable and low scattering background environment.