CRISTINA lucila Josefina
Exciton Autoionization in Ion-Induced Electron Emission
N. BAJALES; L. CRISTINA; S. MENDOZA; R. A. BARAGIOLA; E. C. GOLDBERG; J. FERRON
PHYSICAL REVIEW LETTERS
The American Physical Society
Lugar: Maryland; Año: 2008 p. 227604 - 227607
We report on measurements of electron emission spectra from surfaces of highly oriented pyrolytic graphite (HOPG) excited by 15 keV He+ and Li+ which, for He+, exhibit a previously unreported highenergy 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.