Scanning Tunneling Microscopy in TTF-TCNQ :direct proof of phase and   amplitude modulated charge density waves
  Charge density waves (CDW) have been studied at the surface of a cleaved TTF-TCNQ single crystal using a low temperature scanning tunneling microscope (STM) under ultra high vacuum (UHV) conditions. All CDW phase transitions of TTF-TCNQ have been identified. The measurement of the modulation wave vector along the a direction provides the first evidence for the existence of domains comprising single plane wave modulated structures in the temperature regime where the transverse wave vector of the CDW is temperature dependent, as hinted by the theory more than 20 years ago. 
Zhao Z.Z.Wang, Denis Jerome, Jean Christophe Girard, Claude Pasquier,   Klaus Bechgaard