SINGLE LOCAL SITE STRUCTURE FOR VIBRATIONALLY DISTINCT ADSORPTION STATES - NO ON NI(111)

Scanned energy mode N and O 1s photoelectron diffraction data collected from NO on Ni(111) under conditions corresponding to three distinct N-O vibrational frequencies, previously assigned to different (bridge and atop) local adsorption configurations, show that NO in all cases occupies the same site. Comparison of these data with the results of theoretical simulations indicates that the common site is a threefold coordinated hollow. These results indicate that there is a need to reevaluate the range of applicability of the widely used method of adsorption site assignment based on the numerical values of internal molecular vibrational frequencies.