Abstract
The interaction of nitrogen with a Re(0001) surface has been studied by low energy electron diffraction (LEED), thermal desorption spectroscopy (TDS), Auger electron spectroscopy (AES) and electron energy loss spectroscopy (ELS). Two LEED patterns have been observed upon adsorption of nitrogen on Re(0001). One, identified as the 4 × 1, is induced by N 2 exposure at 115 K and is related to the ordering of molecular nitrogen. Annealing the 4 × 1 phase to 300 K leads to the appearance of a 2 × 2 structure, an ordered structure formed from atomically adsorbed nitrogen, N ads . Two peaks are evident in the TD spectra following N 2 exposure. A low temperature one, α, at ~160 K, whose desorption correlates with the disappearance of the 4 × 1 phase, is believed to correspond to physisorbed N 2 . A second feature, β, between 900 and 1300 K, desorbs with second order kinetics and corresponds to the recombination of N ads . Adsorption of N 2 at 115 K induces sharp electron energy loss peaks at 5, 10, and 15 eV. These loss features disappear at 170 K upon desorption of the α N 2 and are interpreted to correspond to the electronic excitation of molecular nitrogen perturbed by the Re(0001) substrate. The e − -beaminduced dissociation of molecularly adsorbed nitrogen on Re(0001) is also discussed.
Published Version
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