When an electron from one of the lower energy levels collides with another electron in an atom, it is ejected from the atom, thereby forming a gap into which one of the higher-energy electrons can fall, also emitting excess energy.
This energy is emitted in an electron known as an Auger electron and results in an effect called Auger decay. Presently, Guoke Zhao from Tsinghua University in Beijing, China and his collaborators at Sorbonne University in Paris, France have investigated the Auger effect in four hydrocarbon molecules, including cyclohexane, benzene, and larger hydrocarbons.
All the molecules that were investigated were aromatic, meaning they consist of benzene rings with pi bonds, in which atoms that are adjacent to each other share electrons. They identified that molecules consisting of a benzene ring have a lower threshold for Auger decay. Applications include a treatment known as Auger therapy, which is employed in treating cancer patients.
Usually, in Auger decay, atoms are exposed to high-energy X-rays and can be used to analyze the uniqueness of atoms within a substance. However, the Auger effect must be still studied in detail in certain molecules that are essential in day-to-day life, specifically hydrocarbons.
In this research, the scientists investigated the Auger spectra of molecules with the help of computational models. They discovered that molecules with pi electrons have a lower threshold prior to the occurrence of Auger decay than molecules without them. The researchers expect that their work will promote further theoretical and practical studies in this direction.