Mechanism of the Ammonia Molecules Protonation on the Naturally Oxidized Silicon Surface

Authors F.A. Ptashchenko

Odessa State Maritime Academy, 8, Didrikhson Str., 65029 Odessa, Ukraine

Issue Volume 7, Year 2015, Number 3
Dates Received 09 June 2015; published online 20 October 2015
Citation F.A. Ptashchenko, J. Nano- Electron. Phys. 7 No 3, 03027 (2015)
PACS Number(s) 68.43.Bc, 82.65._r
Keywords Quantum chemical calculations (2) , Adsorption (9) , Protonation, Ammonia (2) , Water (10) , Silicon (58) , Silicon oxide.
Annotation The protonation of a single ammonia molecule in the presence of several (1-5) water molecules on the surface of the hydroxylated β-cristobalite surface was studied by means of density functional method with the potential B3LYP using 6-311 ++ g (d, p) basis set in the cluster approximation. The important role of surface OH-groups and H2O molecules in this process is shown. The energy required for the ammonia molecule protonation decreases with the number of adsorbed H2O molecules in the vicinity of this molecule, and the protonation becomes energetically favorable when the adsorbed water molecules form more than one layer. The phenomenon of Si natural surface charging in wet ammonia vapors can also be explained by protonation of NH3 molecules.

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