Scanning tunneling microscopy/scanning tunneling spectroscopy of the organic superconductors (TNTSF)2-PF6 and (TMTSF)2-ClO4

This paper reports on direct observations of the organic superconductors (tetramethyltetraselenafulvalene) (TMTSF)2-PF6 and (TMTSF)2-ClO4 made in air at room temperature. The samples consisted of single crystals electrochemically grown. Images revealing the molecular structural arrangement along different crystallographic orientations will be presented as well as spectroscopic data related to the electronic density of states. The images reveal a structure made up of flat molecules that stack on top of one another to form columns and are responsible for the quasi-one-dimensional nature of the electrical conductivity. Although both materials have similar crystal structure the differences in the symmetry and orientation of the counter anions are not resolved. Tunneling spectroscopy data at room temperature shows no apparent difference in the electronic density of states of both materials