Atom- and radical-surface sticking coefficients measured using resonance-enhanced multiphoton ionization

Sticking coefficients γ of neutral transient species at ambient temperature were measured using in situ resonance enhanced multiphoton ionization (REMPI) of the transients in a low pressure reactor at mTorr pressure. The value of γ for I on a stainless steel surface was 0.16, whereas γ for CF3 free radical on the same surface was <0.01. The REMPI spectrum of SiH2 was observed for the first time, and by the use of different REMPI transitions a value of 0.10 was found for γ(SiH2 ) on a growing carbon-containing hydrogenated silicon surface at ambient temperature. This value increased to 0.15 for interaction of SiH2 with a growing surface containing exclusively Si and H. A lower limit for γ of >0.5 was found for highly vibrationally excited CF3 containing 5900 cm−1 of internal energy and for SiH2 containing 7000 cm−1 of internal energy. The surface was stainless steel in the former case and a carbon-containing Si and H surface in the latter case.