Non-uniform interval-pulse X-ray photon correlation spectroscopy for reduced exposure.

X-ray photon correlation spectroscopy (XPCS) is a powerful technique for evaluating microscopic dynamics using coherent X-rays. Detecting fast or small-scale dynamics typically requires strong illumination and wide-angle scattering detection; however, such conditions can cause non-negligible sample damage. This study presents a non-uniform pulse-interval XPCS approach that enables quantitative dynamical analysis with substantially reduced X-ray exposure. In conventional XPCS, continuous acquisition at uniform time intervals leads to long cumulative exposure, which can introduce radiation-induced artefacts. In this study, only 11 scattering images were recorded at non-uniform intervals, providing a broad range of delay times from a single measurement and enabling dense temporal sampling without increasing the exposure dose. The resulting dataset was analyzed using both XPCS- and X-ray speckle visibility spectroscopy (XSVS)-based schemes, and the results demonstrated that these two independent analyses yield consistent relaxation behaviors. The proposed approach offers an efficient framework for probing complex or non-Brownian dynamics in radiation-sensitive materials and expands the applicability of XPCS to soft and biological systems.