  We study the dynamics of transverse oscillations of a suspended carbon
nanotube into which current is injected from the tip of a scanning tunneling
microscope (STM). In this case the correlations between the displacement of the
nanotube and its charge state, determined by the position-dependent electron
tunneling rate, can lead to a "shuttle-like" instability for the transverse
vibrational modes. We find that selective excitation of a specific mode can be
achieved by an accurate positioning of the STM tip. This result suggests a
feasible way to control the dynamics of this nano-electromechanical system
(NEMS) based on the "shuttle instability".
