appearance energy (appearance potential)

https://doi.org/10.1351/goldbook.A00421
Refers to @[email protected] of a molecule or atom by electron collision or photon absorption. In @[email protected] it has often been reported as the voltage which corresponds to the minimum energy of the electrons in the ionizing beam necessary for the production of a given fragment ion. In @[email protected] it is the minimum energy of the quantum of light which produces @[email protected] of the absorbing molecule.
Sources:
PAC, 1990, 62, 2167. (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2175 [Terms] [Paper]
PAC, 1991, 63, 1541. (Recommendations for nomenclature and symbolism for mass spectroscopy (including an appendix of terms used in vacuum technology). (Recommendations 1991)) on page 1546 [Terms] [Paper]