  In a nanoscale molecular junction at finite bias voltage,the intra-molecular
distribution of vibrational energy can strongly deviate from the thermal
equilibrium distribution and specific vibrational modes can be selectively
excited in a controllable way,regardless of the corresponding mode frequency.
This is demonstrated for generic models of asymmetric molecular junctions with
localized electronic states, employing a master equation as well as a
nonequilibrium Green's function approach. It is shown that the applied bias
voltage controls the excitation of specific vibrational modes coupled to these
states, by tuning their electronic population,which influences the efficiency
of vibrational cooling processes due to energy exchange with the leads.
