ADSORPTION OF NITROGEN-ATOMS ON CU(111), RH(111) AND PT(110) SURFACES

The adsorption of N2 and atomic nitrogen generated in a high-frequency discharge has been investigated on Cu(111), Rh(111) and Pt(110) surfaces with LEED, AES and TDS methods. No adsorption and dissociation of N2 was experienced at 300-600 K under UHV conditions. However, a significant nitrogen adsorption occurred on all surfaces when the N2 gas was atomized by a high-frequency discharge. The concentration of adsorbed N generally 'attained half of the monolayer of surface, metal atoms. Adsorbed nitrogen formed a strong bond with metal surfaces: it desorbed in two stages. The peak temperatures were: 429 and 690-550 K for Rh(111), 467 and 523 K for Pt(110), and 620-677 and 768 K for Cu(111) surfaces. Adsorption of N atoms produced an ordered (2 x 2) LEED pattern (at low coverage) only on Pt surface. At higher coverage, it induced a (1 x 2) --> (1 x 1) change in the periodicity of the reconstructed Pt(110) surface.