UV-Assisted Charge Neutralization for Reliable XPS Measurements on Insulating Materials

When analyzing insulator surfaces using X-ray photoelectron spectroscopy (XPS), spectral shifts and deformations often arise due to surface charging. Although neutralization techniques have been widely adopted to achieve reliable XPS measurements, their effectiveness remains limited, highlighting the need for innovative neutralization strategies. Here, ultraviolet (UV) light irradiation was introduced into XPS measurements. Although it was still impossible to perfectly eliminate the charging effect, stable XPS spectra with reduced and consistent spectral shifts, as well as minimal deformation and broadening, were successfully obtained. Our findings demonstrate that UV light irradiation not only significantly mitigates the intensity of surface charging but also markedly enhances both its temporal stability and spatial uniformity during XPS measurements. Further investigation reveals that the suppression of charging is primarily attributed to the adsorption of UV-excited photoelectrons onto the X-ray-irradiated region. This innovative neutralization method, termed UV-assisted neutralization in this article, was found to be at least as effective as and even superior in maintaining sample integrity to the most commonly used dual-beam charge neutralization, and therefore is expected to become a promising alternative for addressing the charging issues in XPS measurements.