Publication
The Journal of Chemical Physics
Paper

Adsorption of gases activated by electron impact

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Abstract

Adsorption of nitrogen which has been activated by electron impact is shown to result from dissociation of the nitrogen molecule and from the interaction of energetic ions with a nickel surface. Excitation of N2 to states at about 10.3, 12.2, and 14.0 eV causes dissociation. Dissociative ionization at 24.5 eV also leads to additional pumping. Energetic N2+ ions have an adsorption probability of approximately 0.85 when they collide with a nickel surface. It is shown that the ion adsorption probability is practically independent of energy between 30 and 100 eV. It is also shown that thermal energy ions have a very low adsorption probability. These results lead to the postulate that the N2+ ions dissociate in impact and that the atomic nitrogen is subsequently adsorbed. Results have also been obtained which indicate that the adsorption probability of Ar+ is strongly dependent on surface structure. Annealing of the surface greatly reduces the adsorption probability.

Date

02 Jul 2004

Publication

The Journal of Chemical Physics

Authors

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