Johansson, F.O.L.; Cornetta, L.M.; Berggren, E.; Kuklin, A.; Weng, Y.-C.; Sinha, S.; Kühn, D.; Föhlisch, A.; Ågren, H.; Lindblad, A.: A Blyholder mechanism in the chemisorption of N2O on Ni(111) - studied with Auger-photoelectron coincidence spectroscopy. Applied Surface Science 666 (2024), p. 160340/1-11
10.1016/j.apsusc.2024.160340
Open Access Version
Abstract:
In heterogeneous catalysis the surface-adsorbate bond strength is critical for the function of the system. Here we study a series consisting of multilayer, bilayer and monolayer N2O on Ni(111) and employ Auger-photoelectron coincidence spectroscopy (APECS) to study the interaction between the molecule and the substrate directly. We observe intensity in the nitrogen Auger spectra that arise from the interaction between molecule and surface (not observed in free molecules) whereas the oxygen spectra are thickness-independent. Since the two nitrogen atoms of N2O are chemically inequivalent we can assign the intensity present in the bilayer and monolayer cases to orbitals centered on the terminal nitrogen which is closest to the Ni(111) surface. Using ab initio, molecular dynamics and solid-state density functional theory calculations we infer a Blyholder model of the surface bond as consisting of donation from the terminal nitrogen lone-pair valence orbital with back-donation from the metal into the unoccupied orbitals on that nitrogen. This coincidence technique can readily be used to study substrate?adsorbate interactions directly with chemical and orbital specificity - this opens up prospects to study fundamental steps of molecular adsorption and heterogeneous catalysis with unprecedented detail.