DEPOLARIZED LIGHT-SCATTERING FROM DILUTE POLYMER-SOLUTIONS

Depolarized light scattering spectra of chain molecules are analyzed in terms of the contributions of the bond polarizabilities of skeletal and nonskeletal bonds and dipole-induced-dipole interactions between the chain atoms. It is found that substituents lying perpendicular to the chain contour contribute to the high wave vector part of the molecular polarizability. These high k modes are precisely the same as those detected in dielectric and spin relaxation measurements and account for the broad, molecular weight independent background observed in depolarized Rayleigh scattering from polystyrenes. The influence of dipole-induced-dipole interactions on the spectrum is also characterized. Inclusion of these effects gives rise to a weighted sum over several low frequency Rouse-Zimm modes, with the major emphasis coming from the lowest mode. © 1979 American Institute of Physics.