Molecular Raman effect in the optical microcavity: QED vacuum confinement of an inelastic quantum scattering process

The spontaneous Raman scattering from liquid samples of C6H6 is investigated in the Casimir topology of a microscopic optical Fabry-Perot cavity terminated by Bragg reflectors tuned at the emitted Stokes wavelength. The given general quantum scattering theory is based on a complete set of mode functions describing the cavity-confined field in its vacuum state. The coupling of the field with the normal CH ring stretching mode at Delta nu=3062 cm(-1) (totally symmetric species A(1g)) of the benzene molecule is given via the related Raman tensor, which leads to the appropriate form of the coupling Hamiltonian. A detailed experimental investigation of the spontaneous Raman scattering for the mode is then reported. The results confirm the relevant predictions of the scattering theory, namely, the effect of the vacuum confinement on the enhancement and inhibition of the total and differential cross sections, on the angular distribution of the scattered radiation, and on the molecular depolarization ratio.