Design of soft X-ray photon correlation spectroscopy device

Background X-ray photon correlation spectroscopy (XPCS) is a new technique for studying the small-scale relaxation dynamics of condensed matter by using the second order coherence of coherent X-ray scattering. It requires high coherence of incident light. The X-ray interference lithograph (XIL) beamline (BL08U) of Shanghai Synchrotron Radiation Facility (SSRF) uses elliptical polarization oscillator as light source, which has good coherence and high photon flux. It is suitable for the dynamics study of mesoscopic scale electrodes or magnetic micro-regions in ferroelectric and magnetic materials. [Purpose] This study aims to design a set of photon correlation spectroscopy equipment based on soft X-ray. [Methods] Soft X-ray from XIL of SSRF is used as coherent incident beam, and the secondary coherent light is collected, converted and amplified to perform autocorrelation operation. The effects of incident light energy and scattering angle on the scattering vector and period size of sample are discussed. [Results] When the spectral range is 90.5 ∼ 93 eV and the hole diameter is 1 mm, the periodic scales of samples at different positions are 1 ∼ 60 nm. The second-order correlation intensity function of detector arc region is deduced by using Gauss model, and it is used as a function of detection area, photon energy and time. The multiplicative noise of autocorrelation is suppressed by multilayer film polarization extinction. [Conclusion] The development of this device provides a technical approach for better analysis of material dynamics information, and is of great significance. (authors)