ELECTRONIC AND INFRARED PROPERTIES OF THE ALPHA-SEXITHIENYL SINGLE-CRYSTAL

The electronic and vibrational properties of alpha-sexithienyl are investigated by infrared and visible-ultraviolet spectroscopy of the single crystal in polarized light. The aim of this work is to contribute to the understanding of the basic molecular properties of polythiophene of which alpha-sexithienyl is a prototype. An assignment of some infrared active modes is given. The molecule in the crystal appears to be planar. The lowest singlet-singlet allowed electronic transition is polarized parallel to the long molecular axis and a second transition at 370 nm is polarized parallel to the short in plane axis.