Sticking Coefficients and Critical Condensation Conditions of Nickel on Polyfluoroethylene-Propylene

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Abstract
The sticking coefficient and critical condensation of nickel vapor on PFEP (polyfluoroethylene-propylene) substrates have been studied between the incident beam fluxes of 3×1014 and 2×1016 atoms/cm2·sec and the substrate temperatures of 230 and 280°C. Measurements were made by using a separate substrate for each exposure and keeping both the flux and the temperature constant during a run. Experimental results are analyzed by using the atomistic model of nucleation theory by Lewis, which suggests an adsorption energy of nickel atoms on PFEP of 0.8 eV and a critical size of one atom. However, if E a /E b <0.5, pair evaporation becomes more likely than dissociation, and Zinsmeister's theory is plausible. The latter may explain qualitatively the induction periods which have been observed in the sticking coefficient measurements.
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