ROLES OF CENTRAL AND TERMINAL CARBON-ATOMS IN INFRARED AND RAMAN INTENSITIES OF POLYENES - ANALYSIS OF ATOMIC POLAR AND POLARIZABILITY TENSORS

No theoretical and experimental information has been available for the role of each atom in infrared (IR) and Raman spectra of polyene deriv ative systems. Analyzing atomic polar and polarizability tensors at ea ch carbon site in the C=C bond fixed frame, we find that in IR intensi ties, the motions of carbon atoms in the proximity of a substituent ar e important, while in Raman intensities the carbon motions in the cent ral region are important. The strong IR and Raman intensities appear f or the concurrent C=C stretch/contraction motion in nonsymmetric polye nes. (C) 1997 American Institute of Physics.