Abstract Submitted to the    NANOTUBE'04 Conference:

We have performed STM measurements on suspended single wall carbon nanotubes at room temperature in order to probe their intrinsic electronic properties. We find that substrate-nanotube interactions influence the electronic properties. On supported semiconducting nanotubes bands are shifted toward higher energies while they are more symmetric around the Fermi level in the unsupported ones. For metallic tubes we observed that interference patterns of electron waves caused by defects and edges are more pronounced on suspended nanotubes than the supported nanotubes. These results highlight the role of substrate-nanotubes interactions and shed some light on their influences on nanotube devices.