X-ray Photoelectron Spectroscopy (XPS) is a powerful technique used to study the properties of electrons emitted from a sample when it is irradiated with photons. This quantitative spectroscopic method utilises core level shifts to obtain detailed information about the chemical and electronic states of a sample’s elemental components, with a penetration depth of approximately 10-100 Å.
About XPS
Technique
In an XPS experiment, a photon with energy (hv) penetrates the surface of a solid and is absorbed by an electron. If the photon has sufficient energy, it excites the electron from its initial state to an excited state, causing the electron to be emitted as a photoelectron. The energy required for this process depends on the electron’s binding energy in its initial (unbound) state. The energy of the emitted photoelectrons is directly related to their atomic number and the molecular environment from which they originated. Additionally, the number of photoelectrons emitted is proportional to the concentration of the emitting atoms in the sample.
By analysing the energy and intensity of the emitted photoelectrons, XPS provides valuable insights into the elemental composition, chemical state, and electronic properties of the sample’s surface.
Key benefits of XPS
- Enables Detailed Surface Analysis: Allows you to determine the structure of surfaces, interfaces, and surface composition with precision.
- Facilitates Photo-electron Energy Studies: Enables you to investigate the energy of photo-electrons within an atom, offering a different focus compared to XAS, which examines neighbouring atoms.
- Provides Comprehensive Information: Offers both qualitative and quantitative data on the electronic properties and chemical speciation of elements.