Polarization-modulated Fourier-transform infrared reflection absorption spectroscopy has been applied to the characterization of thin films of AIN and Al oxynitride ('AlON') on NiAl(111) and to the observation of surface chemical processes understeady-state conditions in a static NH{sub}3 ambient of up to 200 Torr. AlN films, grown by dosing NiAl(111) with NH{sub}3 at ~1230 K, are found to be structurally inhomogeneous and largely disordered, with no evidence of chemisorption at 300 K in abackground of 200 Torr of NH{sub}3. AlON films, grown by dosing NiAl(111) with NO near 300 K and annealing to 1000 K, appear more homogeneous and show distinct surface and bulk vibrational modes. The former responds reversibly to chemisorbed NH{sub}3which can be detected under steady-state conditions by the appearance of theδ{sub}s, symmetric deformation mode. In comparison to similar results for Al{sub}2O{sub}3, theδ{sub}s frequency indicates a lesser degree of Lewis acidity for the AlON surface.
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