Aniline on Ag(1 1 1): Adsorption configuration, adsorbate–substrate bond, and inter-adsorbate interactions

The adsorption of submonolayer aniline on the Ag(1 1 1) surface has been characterized using temperature programmed desorption (TPD) and electron energy loss spectroscopy (EELS). Analysis of the TPD curves yielded a desorption energy of 74 kJ/mol and revealed repulsive inter-adsorbate interactions resulting from a local dipole moment of 4.3 D at the adsorbate–substrate complex. This dipole moment arises from a weak charge transfer from aniline to silver in forming the adsorption bond. Analysis of the EELS spectrum revealed several vibrational modes that are consistent with weakly chemisorbed aniline with the amino group bound to the surface. Intensity analysis based on IR selection rules on metal shows that the molecule adsorbs nearly flat with a small tilt angle (−13 ± 8° between the CN bond and the surface) and a small orientation angle.