Dynamics of Electron-Induced Manipulation of Individual CO Molecules on Cu(111)

Electrons tunneling from a scanning tunneling microscope tip to individual CO molecules on Cu (111) can cause their hopping from the surface to the tip if the bias exceeds a threshold of 2. 4 V. Polarization- and time-resolved two-photon photoemission identifies the underlying elementary process as intermediate population of a CO 2^*-derived level, which exhibits an ultrashort lifetime of 0. 8--5 fs. From an isotope effect of 2. 7-₀. ₅^+0. 3 it can be calculated that 0. 05% of the tunneling current transiently occupies this level while a desorption of the excited molecule occurs only in 510^-9 of the cases.