High-resolution X-ray absorption spectra of the π∗ resonance of N2 directly physisorbed on Cu(1 0 0)

High-resolution NEXAFS spectra of the π∗ resonance of N2 molecules directly physisorbed on a Cu(1 0 0) surface are reported. The vibrational fine structure of this resonance, even for very low coverages, could be resolved, allowing the performance of a vibrational analysis of the experimental spectra. We obtain changes in the vibrational properties of the physisorbed molecules compared to those in the gas~phase. This is due to the direct adsorbate–substrate interaction for N2 coverages up to 1 ML and to the adsorbate–adsorbate interaction for the multilayer.