Synchrotron-radiation study of the five-dimensional modulated phase of tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) at 15 K

Abstract

The 2${\mathrm{k}}_{\mathrm{F}}$ modulated structure of tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) at 15 K has been analyzed by use of a set of satellite intensities collected at the National Synchrotron Light Source. The analysis in the five-dimensional superspace group P:P${2}_{1}$/c:cmm shows the largest modulation to be a slip of the TTF molecules with an amplitude of about 0.02 A\r{}, in the direction of the long molecular axis of the molecule. The TCNQ translational modulations are similar, but of much smaller magnitude . Rotations about the long molecular axes of both type of molecules are also observed.