Meaning
Surface analysis method measures the kinetic energy of electrons ejected from a sample by incident photons. Application of photoelectron spectroscopy provides a detailed map of the elemental composition and chemical states within the top ten nanometers of a surface. This sensitivity makes it the primary tool for studying the solid electrolyte interphase in batteries.
Binding Energy
Kinetic energy measurements are subtracted from the incident photon energy to determine the strength of the electron-nucleus bond. In photoelectron spectroscopy, this value acts as a fingerprint for identifying specific elements. Shifting the energy of the incident x-rays allows for the probing of different atomic shells.
Chemical Shift
Electronic environment of an atom alters the binding energy in a predictable way. Photoelectron spectroscopy detects these small variations to distinguish between different oxidation states or bonding partners. For example, a carbon atom in a polymer chain shows a different peak position than a carbon atom in a metal carbide.
This distinction is necessary for verifying the success of surface treatments or coating processes.
Depth Profiling
Ion sputtering is used to remove layers of the sample between successive measurements. This technique allows photoelectron spectroscopy to reveal the composition gradient from the surface into the bulk material. It is commonly used to measure the thickness of passivating oxides on metal foils.
