Effects of projectile track charging on the H^- secondary ion velocity distribution

Abstract:

The bombardment of insulating targets by MeV projectiles produces a positive track delivering secondary electrons to the solid. These electrons are eventually captured by adsorbed hydrogen-containing molecules, inducing fragmentation and initiating the H- secondary ion emission. The dynamics of this process is very sensitive to the track electric field and depends on the emission site and on the H- initial velocity. In this work, a model, based on a time-depending track potential followed by secondary electron induced desorption - SEID, is employed to describe the production and dynamics of H- secondary ion emission. It is shown that depending on how fast the track neutralization occurs, the movement of H- ions may be accelerated, decelerated or even aborted. Trajectories, angular distributions and energy distributions are predicted and compared with experimental data obtained for water ice bombarded by 1.7 MeV nitrogen ions. © 2006 Elsevier B.V. All rights reserved.

Año de publicación:

2007

Keywords:

• SEID
• Sputtering
• XY-TOF
• Ion solid interaction
• Secondary ion emission
• Energy and angle differential spectrometry
• H desorption -

Fuente:

scopus