The paper analyzes Surface Enhanced Raman Scattering (SERS) and Surface Enhanced Hyper Raman Scattering (SEHRS) spectra of 4,4'-bypiridine molecule for two possible geometries, which are described by D2 and D2h symmetry groups. It is pointed out on appearance of sufficiently strong lines, caused by vibrations with the unit irreducible representation for both possible configurations. Appearance of these lines in the SEHRS spectrum points out the existence of a strong quadrupole light-molecule interaction. In addition one observes the lines, caused by vibrations both with the unit irreducible representations A or Ag and the irreducible representation B1 or B1u. The last ones describe transformational properties of the dz component of the dipole moment, which is perpendicular to the surface. This property of the spectrum is caused by peculiarity of the geometry of the molecule, which consists of two benzene rings, which are weakly connected with each other. The linear combinations of the vibrations of the rings create two nearly degenerated symmetric and anti symmetrical states, which cannot be identified in the experimental spectra. The result is in a full agreement with the dipole-quadrupole theory of SERS and SEHRS.

Original languageEnglish
Pages (from-to)1368-1376
Number of pages9
JournalPhysics of the Solid State
Volume59
Issue number7
DOIs
StatePublished - 1 Jul 2017

    Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

ID: 43849028