title: Exciton autoionization in ion-induced electron emission.
abstract: We report on measurements of electron emission spectra from surfaces of highly oriented pyrolytic graphite (HOPG) excited by 1-5 keV He+ and Li+ which, for He+, exhibit a previously unreported high-energy structure. Through a full quantum dynamic description that allows for the calculation of neutralization and electron-hole pair excitation, we show that these high-energy electrons can arise from autoionization of excitons formed by electron promotion to conduction band states close to the vacuum level. The same calculation explains the observed absence of high-energy excitons for Li+ on HOPG.
authors.affiliation: Instituto de Desarrollo Tecnológico para la Industria Química, CONICET, Santa Fe, Argentina.
authors.forename: N
authors.initials: N
authors.lastname: Bajales
authors.forename: L
authors.initials: L
authors.lastname: Cristina
authors.forename: S
authors.initials: S
authors.lastname: Mendoza
authors.forename: R A
authors.initials: RA
authors.lastname: Baragiola
authors.forename: E C
authors.initials: EC
authors.lastname: Goldberg
authors.forename: J
authors.initials: J
authors.lastname: Ferrón