Molecular Scattering of Light in Gases

Structure and NLO properties of halogen (F, Cl) substituted formic acid dimers

“…The molecular scattering of light provides a great spread of information about the details of phenomena observed in the interaction of radiation with matter [80][81][82][83]. The scattering of light off molecules occurs in two ways, elastic and inelastic.…”

Light scattering from disordered media

“…Indeed, in the harmonic approximation, equation (14) is still directly related to the density of states of the excitations, even if these are somewhat localized. If we use the displacement correlation function of equation (7) to describe the mode localization the factor containing the correlation length Ak vanishes in equation (14) since the absence of orientational correlation has selected only the l=l' terms. In such a way the frequency spectrum loses any dependence from this parameter and equations (15) and (16) may be formally retained also in the case of topologically disordered systems.…”

“…and translational collective modes. These couplings have already been widely investigated in crystals, amorphous, solids [14] and liquids [17,18] and are known to give rise to depolarized contributions to the light scattering, arising only from transverse and longitudinal modes having wavevector k_~ q. …”

“…The intensity scattered by a sample at a frequency % and shifted by an amount ~o = co i -oJs from the incoming frequency co i can be written in terms of the space-time Fourier transform of the induced dipole moment correlation function [14] I(w)oc Ells dr1 dr~ dt exp (-iq{rl-rz}+ioJt)(Fi(rt, t)Fj(r 2, 0)), (1) where q is the exchanged wavevector and/&(r, t) are the cartesian components of the macroscopic dipole moment induced at point r and time t by the external field E o exp (iwit). If we assign to each molecule an individual induced dipole moment l~z(t), we may write :…”

“…If vq l and 6t are the angles in the laboratory frame of the principal axis of the polarizability ellipsoid for the/th molecule (supposed to be a symmetrical top) the angular dependence of ti/may be represented as [14] where till, and B is the magnitude of the anisotropic molecular polarizability [6].…”