electron affinity, E ea

Energy required to detach an electron from the singly charged negative ion (energy for the process E01977-1). The equivalent more common definition is the energy released (E initital − E final) when an additional electron is attached to a neutral atom or molecule.
Source:
Green Book, 2nd ed., p. 20
PAC, 1994, 66, 1077 (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1109
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