Charge density waves in quasi-one-dimensional thallium overlayers

Using the techniques of LEED, AES, UPS and changes in secondary electron emission (SEECC), the authors have studied thallium chains adsorbed on copper (100). Their results indicate the existence of two one-dimensional phases. They have shown that the lower-density phase undergoes a spontaneous (Peierls) distortion. Within error limits, there is agreement between LEED and angle-resolved UPS data that the periodic distortion resulting from the charge density wave repeats every eighth thallium atom in the chain structure. The magnitude of the gap at the Fermi level resulting from the distortion has been estimated to be 0.34 eV.