Rayleigh and hyper-Rayleigh magnetic optical activity of molecular systems with orbital degeneracy

Abstract

Linear and non-linear light scattering in static magnetic fields by molecules with orbitally degenerate ground states is investigated. The temperature dependent circular intensity difference (CID) spectrum induced by the orientational mechanism is calculated by taking into account the rotational diffusion. It is shown that the presence of degeneracy is a sufficient condition for temperature dependent CID occurrence both in Rayleigh and hyper-Rayleigh scattering; the selection rules determining the appropriate symmetry of the molecular ground states are obtained. The differences between two cases, the spin-only (Kramers) degeneracy and the orbital degeneracy, are discussed; the temperature dependent optical activity in light scattering is possible even if the antisymmetric scattering is neglected. The role of spin-orbit coupling in the generation of optical activity of molecules with G 3/2 ground terms is discussed. Examples of molecular systems are suggested, in which the new phenomena revealed in this wo...