  The transport properties of a suspended carbon nanotube probed by means of a
STM tip are investigated. A microscopic theory of the coupling between
electrons and mechanical vibrations is developed. It predicts a
position-dependent coupling constant, sizeable only in the region where the
vibron is located. This fact has profound consequences on the transport
properties, which allow to extract information on the location and size of the
vibrating portions of the nanotube.
