AVS 51st International Symposium
    Applied Surface Science Monday Sessions
       Session AS-MoM

Paper AS-MoM9
Ionization of Al Atoms Emitted from Al Metal

Monday, November 15, 2004, 11:00 am, Room 210A

Session: SIMS I - Cluster Probe Beams and General Topics
Presenter: X. Chen, University of California, Riverside
Authors: X. Chen, University of California, Riverside
Z. Sroubek, Czech Academy of Sciences, Czech Republic
J. Yarmoff, University of California, Riverside
Correspondent: Click to Email
Ion-surface charge exchange is a central process in many surface analysis techniques, such as ion scattering spectroscopy (ISS), secondary ion mass spectrometry (SIMS) and electron stimulated desorption (ESD). Recently, we achieved a better understanding of homogeneous charge exchange between metal ions and metal surfaces, which gives a general insight for all the above techniques and is especially critical in analysis of SIMS data. Atomically clean and modified Al (100) surfaces in ultra-high vacuum were bombarded by 2 and 5 keV Xe@super +@ ions. The absolute ionization probability of energetic (> 500 eV) recoiled particles was measured with time-of-flight, and then used to calibrate the energy and angular distributions of low energy (10-600 eV) sputtered ions collected with an electrostatic analyzer. The independent particle model of non-adiabatic surface-atom charge-exchange, which has typically been used to analyze single scattering events, is shown to accurately describe all of the experimental data from a few eV (typical sputtering energy) to the keV (typical scattering and recoiling energy) range. Extensions of this work to other clean metal surfaces, such as Fe, which has a d-band, will be discussed. Also, we plan to perform homogeneous scattering experiments with a novel liquid metal ion source (LMIS), to determine absolute homogeneous ionization probabilities for well-defined trajectories.