X-ray photoelectron spectroscopy (XPS) Nexsa

ThermoFisher Scientific Nexsa

X‑ray photoelectron spectroscopy (XPS) is a powerful surface‑analysis technique that reveals the elemental composition and chemical states within the top few nanometers of a material. Monoenergetic X‑ray photons eject core electrons from atoms in the studied material. These electrons (photoelectrons) leave the sample with a specific kinetic energy equal to the difference between the incident photon energy and the binding energy plus the work function that must be overcome to liberate the electron. The photoelectrons then travel to the hemispherical analyzer, where their count and kinetic energy are measured and the corresponding binding energies are calculated. Each chemical element exhibits characteristic binding‑energy values that act as a unique fingerprint. Moreover, every chemical bond shifts these energies by a small but highly specific amount. Thanks to the high resolution of modern XPS systems, it is possible to determine both the chemical composition and the chemical states (bonding environments) present in the material.

This particular XPS system is equipped with a monochromated Al Kα X‑ray source and a 128‑channel hemispherical analyzer. The chamber is continuously pumped by two turbomolecular pumps, an automated titanium sublimation pump, and a backing pump, together maintaining ultra‑high‑vacuum conditions. This setup enables fast chemical analysis of the topmost surface layer—typically only a few nanometers deep—across an energy range from 1400 eV to –10 eV, with a resolution of up to 0.01 eV.

With a wide range of spot sizes from 10 μm to 400 μm, the system also supports chemical imaging of surface composition, which is particularly valuable for samples with low homogeneity or microstructured patterns. A monatomic Ar ion source is available for sputter etching and depth profiling, while a Joule source provides charge compensation. Rotating and tilting sample stages enable advanced depth‑profiling geometries and angle resolved XPS (ARXPS).

This state‑of‑the‑art tool provides essential insights into advanced materials and plays an irreplaceable role in thin‑film research