Raman scattering tensors of 5-iodouracil.

Polarized Raman scattering measurements have been made of a single crystal of 5-iodouracil by the use of a Raman microscope with the 488.0 nm excitation. The crystal belongs to space group P2(1) (monoclinic), and Raman scattering intensities, corresponding to the a'a', bb, cc, a'b and bc components of the crystalline Raman tensor, have been determined for each prominent Raman band, where a' is the axis perpendicular to the c axis in the ac plane. From these experimental results, the shapes and orientations of the Raman scattering tensors have been derived for 6 base vibrations in the 5-iodouracil molecule. By comparing these tensors with those for thymine and pseudouridine vibrations, discussions were made of the polarizability oscillations caused by the normal vibrations localized in the pyrimidine base.