Manifestation of Strong Quadrupole Light-Molecule Interaction in the SER   and SEHR Spectra of Pyrazine and Phenazine
  It is demonstrated that explanation of appearance of strong forbidden lines in the SEHR spectra of pyrazine and phenazine, caused by totally symmetric vibrations and also other details of their SER and SEHR spectra can be made on the base of the dipole-quadrupole theory. The main point of this theory is conception of a strong quadrupole light molecule interaction, arising in surface fields strongly varying in space near a rough metal surface. Existence of the pointed lines is a good corroboration of existence of the strong quadrupole light-molecule interaction. 
A.M. Polubotko
physics.optics physics.chem-ph