X-ray photoelectron spectroscopy (XPS) measures the binding energy of core-level electrons, which are well-localised to specific atomic sites in a molecular system, providing valuable information on the local chemical environment. The technique relies on measuring the photoelectron spectrum upon x-ray photoionisation, and the resolution is often limited by the bandwidth of the ionising x-ray pulse. This is particularly problematic for time-resolved XPS, where the desired time resolution enforces a fundamental lower limit on the bandwidth of the x-ray source. In this work, we report a novel correlation analysis which exploits the correlation between the x-ray and photoelectron spectra to improve the resolution of XPS measurements. We show that with this correlation-based spectral-domain ghost imaging method we can achieve sub-bandwidth resolution in XPS measurements. This analysis method enables XPS for sources with large bandwidth or spectral jitter, previously considered unfeasible for XPS measurements.

X 射线光电子能谱 (XPS) 测量核心级电子的结合能，这些电子很好地定位于分子系统中的特定原子位点，提供有关局部化学环境的宝贵信息。该技术依赖于测量 X 射线光电离时的光电子谱，分辨率通常受到电离 X 射线脉冲带宽的限制。这对于时间分辨 XPS 尤其成问题，其中所需的时间分辨率对 X 射线源的带宽施加了基本的下限。在这项工作中，我们报告了一种新的相关分析，它利用 X 射线和光电子光谱之间的相关性来提高 XPS 测量的分辨率。我们表明，使用这种基于相关性的谱域重影成像方法，我们可以在 XPS 测量中实现子带宽分辨率。这种分析方法为具有大带宽或频谱抖动的源启用 XPS，以前认为 XPS 测量不可行。