Time-of-Flight Measurements of Nonlinear Effects in Sputtering by Dimer Ions

Time-of-flight distributions of sputtered Au atoms have been measured under 4 ke V I⁺ and 8 keV I₂⁺ impact. The results show that a developing thermal spike contributes to the sputtering yield. It is higher under I₂⁺ bombardment but the measured temperature obtained from Maxwell-Boltzmann fits is lower, suggesting a lower effective surface binding energy U₀ for I₂⁺ bombardment. A correlation between spike temperatures and U₀ is discussed.