Auger electron spectroscopy (AES), in conjunction with argon ion sputtering/depth profiling have been used to study the nature of nickel substrates nitrided by chemical modification with hydrazoic acid (HN3) and nitrogen ion implantation. Nickel-nitrogen bond formation was evidenced from both treatment strategies, although a thicker nitrided overlayer was observed during nitrogen ion implantation. For ion implantation, the rate of surface nitridation was found to be independent of ion energy in the range of 2-5 keV, although at higher beam energies thicker nitride films were produced. The Ni-N bond was stable under vacuum conditions until approximate to650 K. The influence of the surface chemical composition on the N(KLL) AES transition in metal-nitrogen (M-N) containing compounds is also illustrated for Ni, Al, and NiAl substrates exposed to HN3. (C) 2002 Elsevier Science B.V. All rights reserved.