Interactions of nitrogen with Ni(110) — EELS, AES and LEED studies

Abstract

The interactions of nitrogen with an Ni(110) surface at both 90 and 300 K have been investigated by means of high-resolution vibrational electron energy loss spectroscopy (EELS). Auger electron spectroscopy (AES) and low-energy electron diffraction (LEED). N 2 molecules are chemisorbed nondissociatively at 90 K, and are desorbed at ~170 K. N 2 molecules are not adsorbed on Ni(110) at 300 K, however, as the Ni(110) surface is exposed to a mixture of N 2 molecules and N atoms at 300 K, N 2 admolecules (double- and triple-bonded N 2) are formed in addition to N adatoms (which are located, most probably, in the long-bridge, short-bridge and on-top sites, and also in the “subsurface” and “bulk”). It is suggested that N 2 admolecules are formed in the “active sites” on the Ni(110) surface which is distorted by the adsorption of N atoms. Thermal treatment of the (N 2 + N)-exposed Ni(110) surface is discussed. The N 2 admolecules ormed by the (N 2 + N) exposure are desorbed at ~400–450 K. The (2 × 3)-N structure is formed by heating at ~650–780 K. The Ni(110)-(N 2 + N) interaction is compared with the Pd(110)-(N 2 + N) interaction.