When an electron from one of the lower energy levels in an atom is knocked out of the atom, it creates a space which can be filled by one of the higher-energy electrons, also releasing excess energy. This energy is released in an electron called an Auger electron - and produces an effect known as Auger decay. Now, Guoke Zhao from Tsinghua University in Beijing, China and colleagues at Sorbonne University in Paris, France have studied the Auger effect in four hydrocarbon molecules: benzene, cyclohexane, hexatriene and hexadiene. These molecules were chosen because they exhibit different characteristics of aromaticity. The authors found that molecules containing pi bonds have a lower threshold for Auger decay.
Potential applications of this decay effect include a treatment called Auger therapy, which is used to help cancer patients. Auger decay often involves atoms being subjected to high-energy X-rays, and can be used to study the identity of atoms within a substance. But the Auger effect has yet to be thoroughly studied in certain molecules that are important in everyday life, particularly hydrocarbons.
In this article in EPJ D, the researchers studied the Auger spectra of molecules using computational models. They found that molecules with pi electrons have a lower double ionization threshold thus favoring Auger decay compared to saturated hydrocarbons. The authors hope their work will encourage further theoretical and experimental investigations in this direction.
G. Zhao, T. Miteva, N. Sisourat (2019) Inner-valence Auger decay in hydrocarbon molecules, European Physical Journal D 73: 69, DOI: 10.1140/epjd/e2019-90529-x