Keywords
Photoionization
Photoelectron spectroscopy
Auger electron spectroscopy
Threshold photoelectron spectroscopy (TPES)
PEPICO
TPEPICO
PEPECO
TOF-PEPECO
Synchrotron radiation
Metrica
How to Cite
Abstract
The rigorous determination of ionization energies is fundamental to understanding the electronic and structural properties of atoms and molecules. The present text is a review that compares the main experimental spectroscopic techniques employed in this determination, highlighting their principles, instrumental requirements, applications, and limitations. Initially, we discuss photoelectron spectroscopies in the ultraviolet (UPS) and X-ray (XPS) regions, employed in the determination of single ionization energies. Subsequently, threshold photoelectron spectroscopy (TPES) is presented, which offers high resolution and versatility in the variation of photon energy. The PEPICO, TPEPICO, PEPECO, and TOF-PEPECO coincidence techniques are also discussed, as they correlate the detection of photoelectrons and photoions, enabling a detailed investigation of fragmentation processes and multiple ionization. These approaches provide complementary information on the final electronic states and dissociation mechanisms, thereby expanding our understanding of ionization dynamics in gaseous and complex molecular systems. It is concluded that the choice of the most appropriate technique depends on the nature of the system under study, the available experimental conditions, and the type of spectroscopic information sought.
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