X-ray photon correlation spectroscopy (XPCS) is a coherent scattering technique used to probe the dynamic properties of materials by recording a fluctuating speckle pattern. Recent advancements have expanded its application to study nonequilibrium and heterogeneous dynamics across a wide range of condensed matter and materials [1-4]. In this talk, I will focus on soft matter application with two examples from our recent work. The first study investigate the dynamics of protein thermal gel using XPCS in the Ultra-small-angle X-ray scattering (USAXS) mode [1]. This approach probes length scales of a few hundred nanometers, consistent with the mesh size of gels, and reveals slow dynamics occuring on timescales exceeding seconds. The results suggest that the microscopic dynamics exhibit hyper-diffusive behavior driven by internal stress relaxation. The second example demonstrates the capability of Megahertz XPCS at X-ray free electron laster facilities to resolve protein diffusion within crowded environments [3]. This approach bridges a critical gap in the spatio-temporal resolution of soft matter and biological systems by capturing molecular diffusion on microsecond timescales.

　　References

　　1. N. Begam, et al. Phys. Rev. Lett., 126, 098001 (2021)

　　2. A. Girelli, et al. Phys. Rev. Lett., 126, 138004 (2021)

　　3. M. Reiser, et al. Nature Commu., 13, 5528 (2022)

　　4. N.D.Anthuparambil, et al. Nature Commu., 14, 5580 (2023)