Laboratory-Based Ambient-Pressure X-ray Photoelectron Spectroscopy for Pressure up to 1 bar

This is the authors' abstract. We don't add key points for this paper.

Ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) is a rapidly developing technique with broad applications in surface science, catalysis, energy materials, and environmental science. In this study, we present a laboratory-based AP-XPS system that integrates the de Laval nozzle technology to generate a supersonic gas jet. The gas jet creates an ultrathin high-pressure (up to 1 bar) region directly above the sample surface, enabling XPS measurements at 1 bar with a laboratory-based AP-XPS system. The surface pressure was validated by using both a custom-built offline pressure measurement system and computational fluid dynamics simulations. Owing to its limited thickness (∼20 μm), this high-pressure region effectively minimizes gas–electron scattering under elevated pressures. Moreover, the gas delivery design establishes a localized low-pressure zone near the front cone, significantly reducing the load on the differential pumping stage. The method achieves XPS measurements at 1 bar, enhancing a laboratory-based AP-XPS platform for true ambient pressure characterization under certain industrially relevant catalytic conditions.