Electroionization study of ethane: structures in the ionization and appearance curves

Abstract

Ionization efficiency curves of very high signal-to-noise ratio are presented for ethane and most fragment ions containing at least one carbon atom. These curves, which are produced by monoenergetic electron impact, extend up to 10 eV above the initial onsets. Novel structures are observed in most curves. Certain features appear at the same energy in several of the curves indicating that they belong to a common progenitor, either [Formula: see text] or [Formula: see text], and not directly to the detected ions. These sets of structure are attributed to negative ion states (Feshbach resonances) and/or to Rydberg autoionizing states.