Sputtered neutral SinCm clusters as a monitor for carbon implantation during C60 bombardment of silicon

The incorporation of carbon atoms into a silicon surface under bombardment with 40-keV C60+ ions is investigated using time-of-flight mass spectrometry of sputtered neutral and ionized SinCm clusters. The neutral particles emitted from the surface are post-ionized by strong field infrared photoionization using a femtosecond laser system operated at a wavelength of 1400/1700 nm. From the comparison of secondary ion and neutral spectra, it is found that the secondary ion signals do not reflect the true partial sputter yields of the emitted clusters. The measured yield distribution is interpreted in terms of the accumulating carbon surface concentration with increasing C60 fluence. The experimental results are compared with those from recent molecular dynamics simulations of C60 bombardment of silicon.