In this contribution, we will show that single-molecule spectroscopy should provide a very sensitive probe for the motion of nanoresonators. Free from ensemble averaging, small shifts of the narrow single molecule optical lines induced by an external perturbation can be measured with high accuracy at liquid Helium temperatures. When embedded in a solid matrix, certain fluorescent molecules usually gain permanent electric dipole moments due to distortions by the surrounding matrix. These molecules display a linear stark shift and their transition frequency can be used to probe external electric field changes.

We propose to use single molecules to probe the electric field between the substrate and a carbon nanotube, attached to an AFM tip and brought close to the molecule. The thermal vibrations of the nanotube can thus be directly monitored on the molecule fluorescence excitation spectrum. We formulate a system of Bloch-Langevin equations describing a two-level system (the molecule) coupled to an oscillator (vibrating nanotube), and analytically obtain the solution of this system of equations in various limits. We recover many of the features characteristic of the situation when the molecule is driven by laser and a radio frequency field [2] (instead of the oscillator). There are, however, many important differences, particularly, the widths of the satellite peaks and the distribution of their heights, which allow extracting the information about the parameters of the oscillator via the spectroscopic measurements of the single molecule luminescence. The proposed setup can be also potentially used for cooling the nanotube oscillator.

[1] Ph. Tamarat, A. Maali, B. Lounis, and M. Orrit, Ten years of single-molecule spectroscopy, J. Phys. Chem. 104, 1 (2000).

[2] Ch. Brunel, B. Lounis, Ph. Tamarat, and M. Orrit, Rabi resonances of a single molecule driven by rf and laser fields, Phys. Rev. Lett. 81, 2679 (1998).