Vibrational assignments in the conductivity spectra of semiconducting (TMTSF)2ReO4 and (TMTSF)2BF4 (where TMTSF is tetramethyltetraselenafulvalene) for radiation polarized perpendicular to the chains.

We present a vibrational analysis of the transverse {bold E}{parallel}{bold b}{prime} conductivity of semiconducting (TMTSF){sub 2}ReO{sub 4} and (TMTSF){sub 2}BF{sub 4} (where TMTSF is tetramethyltetraselenafulvalene). We also report the results of a normal-coordinate calculation of the vibrations of the deuterated (TMTSF){sup +} molecule, which was used to assist in the reported assignments. The data were supplemented with powder spectra, which showed predominantly the infrared-active {ital b}{sub 1{ital u}} modes. The {bold E}{bold b}{prime} spectra displayed the expected infrared-active {ital b}{sub 2{ital u}} modes, as well as several totally symmetric {ital a}{sub {ital g}} modes resulting from the general site symmetry of the molecule. Unusual strength is noticed in the two {ital b}{sub 2{ital u}} modes which are almost degenerate with the very intense {nu}{sub 4}({ital a}{sub {ital g}}) doublet observed in the {bold E}{bold a} spectra. In that polarization the strength is derived from electron-phonon coupling. There is, however, no such coupling observed in the {bold E}{bold b}{prime} polarization.