Cross-section and selection rules in surface enhanced hyper Raman   scattering
  The expression for the SEHR cross-section of symmetrical molecules within the framework of the dipole-quadrupole theory is obtained. It is formed by contributions, which depend on various dipole and quadrupole moments. Estimation of the enhancement coefficients for the quadrupole enhancement mechanism in some limited case can achieve the value . It is demonstrated that the contributions follow some selection rules. Qualitative classification of the contributions after the enhancement degree is given. 
A.M. Polubotko
physics.chem-ph physics.optics