Two-dimensional correlation analysis for X-ray photoelectron spectroscopy

• Published in: Journal of physics. B, Atomic, molecular, and optical physics Vol. 54; no. 14
• Main Authors: Li, Siqi, Driver, Taran, Al Haddad, Andre, Champenois, Elio G., Agaker, Marcus, Alexander, Oliver, Barillot, Thomas, Bostedt, Christoph, Garratt, Douglas, Kjellsson, Ludvig, Lutman, Alberto A., Rubensson, Jan-Erik, Sathe, Conny, Marinelli, Agostino, Marangos, Jon P., Cryan, James Patrick
• Format: Journal Article
• Language: English
• Published: United States IOP Publishing 25.11.2020
• Subjects: AMO physics; free-electron laser; ghost imaging; OTHER INSTRUMENTATION; x-ray potoelectron spectroscopy
• ISSN: 0953-4075; 1361-6455

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.