We report observations of electron emission from MgO surfaces induced by impact of 100 eV–4 keV He+, Na+, Ne+,Ar+ ions. The energy distribution of emitted electrons is nearly independent of ion type and energy, showing that it iscaused by the decay of an intrinsic electronic state of the solid excited by the ions. The similar yields and energy distributionsfor incident Na+ and Ne+ ions rule out the potential mechanism of electron emission. The results are consistentwith a novel model in which excitation occurs when electrons centered at the oxygen anions are promotedduring a collision with the projectile (kinetic mechanism), and transferred to a surface exciton that can autoionize sinceit lies above the vacuum level, as determined by combining measurements of electron energy loss and photoelectricthreshold.
Ion-induced electron emission from MgO by exciton decay into vacuum
RICCARDI, Pierfrancesco;
2004-01-01
Abstract
We report observations of electron emission from MgO surfaces induced by impact of 100 eV–4 keV He+, Na+, Ne+,Ar+ ions. The energy distribution of emitted electrons is nearly independent of ion type and energy, showing that it iscaused by the decay of an intrinsic electronic state of the solid excited by the ions. The similar yields and energy distributionsfor incident Na+ and Ne+ ions rule out the potential mechanism of electron emission. The results are consistentwith a novel model in which excitation occurs when electrons centered at the oxygen anions are promotedduring a collision with the projectile (kinetic mechanism), and transferred to a surface exciton that can autoionize sinceit lies above the vacuum level, as determined by combining measurements of electron energy loss and photoelectricthreshold.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
