THE INTERACTION OF NITROGEN WITH TITANIUM STUDIED BY SOFT-X-RAY ABSORPTION-SPECTROSCOPY - ADSORPTION VERSUS IMPLANTATION

The interaction of nitrogen with titanium has been studied by means of N ls X-ray absorption spectroscopy (XAS). It is shown that N Is XAS spectra provide useful chemical information on this system. The spectra of nitrogen adsorbed on Ti indicate strong Ti 3d-N 2p and Ti 4sp-N 2p interactions. The Ti 3d states are split by crystal field effects and are strongly hybridized to N 2p orbitals. In comparison with a N 1s XAS spectrum from a reference TiN sample the spectra indicate a clear chemical similarity between the nitrogen chemisorbed layer on Ti and TiN bulk. In the case of the spectra of N+ implanted in Ti, similar features to the above, at low primary beam energies (250 eV), are observed whereas at higher energies (above 1 keV) the spectra show a sharp quasi-atomic absorption peak which is attributed to weakly bonded N atoms in the bulk. The spectra also reflect disorder in the implanted layer and the two-dimensional character of the chemisorbed layer.