Vibrational spectroscopy of CO/Cu(211) with a CO terminated tip

Vibrational excitations of an isolated CO molecule adsorbed on a Cu(211) su rface have been, for the first time, observed with a CO terminated scanning tunneling microscope tip. Both the frustrated translational and rotational modes were observed, and in agreement with the case of a metallic tip. The presence of a CO molecule on the tip, transferred by controlled vertical m anipulation, strongly influences the frustrated translational mode of the C O molecule, while it does not affect the frustrated rotational mode. The pr esent work demonstrates that scanning tunneling vibrational spectroscopy is also possible with a molecule at the end of the tip, opening new interesti ng fields of research and putting some more light on the still open questio n of inelastic tunneling and its selection rules.