photoelectron Syllabification: (pho·to·e·lec·tron)Pronunciation: /ˌfōtōiˈlekˌträn/Definition of photoelectron noun an electron emitted from an atom by interaction with a photon, especially an electron emitted from a solid surface by the action of light. Derivatives photoelectronicPronunciation: /-ilekˈränik/ adjective photoelectron in other Oxford dictionaries Definition of photoelectron in the British & World English dictionary