Photonics

Biography

Biography: Aleksey Mickhailovich Polubotko

Abstract

At present it is well proved in our works that the reason of SERS, SEHRS and SEIRA is so-called strong quadrupole light-molecule interaction, which arises in surface electromagnetic fields strongly varying in space near a rough metal surface. This interaction is associated with terms of the light-molecule interaction Hamiltonian with the quadrupole moments  and , or their linear combinations transforming after the unit irreducible representation of the molecule symmetry group, which  results in appearance of strong forbidden lines in molecules with sufficiently high symmetry. The general requirement for observation of these lines is belonging of the molecule to the symmetry group, where the component of the dipole moment , which is perpendicular to the surface transforms after the irreducible representation another, than the unit one. However, it appears that for the molecules, which belong to the cubic symmetry groups  and the icosahedral groups  and  the strong quadruple light-molecule interaction, is forbidden due to specificity of these groups and the electrodynamic law. Therefore, the light-molecule interaction in these molecules is of a purely dipole type. This property must result in the absence of the lines with the unit irreducible representation in the SEIRA and SEHRS spectra of molecules, belonging to these groups. The absence of the indicated lines at 496 and 1470  was observed in fullerene  that strongly supports the Dipole-Quadrupole theory of the indicated processes.