Manifestation of strong quadrupole light-molecule interaction in the SEIRA spectra of some symmetrical molecules

► Here we analyze the SEIRA spectra of BiPyH22+ and ethylene, adsorbed on copper. ► In addition we analyze the SEIRA spectrum of ethylene, adsorbed on mordenites. ► There are forbidden bands in these spectra. ► They are caused by vibrations with the Ag unit irreducible representation. ► Their appearance can be explained by the Dipole-Quadrupole Theory of SEIRA.