Influences of the incident He* velocity on metastable de-excitation processes at a Cs-covered Si(1Â 0Â 0) surface

With increasing He* velocity, the relative weight of the peak from the decay of He*−(1s2s2) in the spectrum was decreased, which means the auto-detachment process becomes more important than the Auger de-excitation process. The low-energy threshold of the spectrum shifted to higher energies with higher He* velocities. This implies that the surface electronic states are distorted by incident atoms, and, consequently, the surface potential barrier is increased.