title: Electron stimulation of internal torsion of a surface-mounted molecular rotor.
abstract: A molecular rotor which includes a central rotator group was investigated by scanning tunneling microscopy at 4.9 K as it was grafted on a Cu(111) surface via its two terminal groups. Topographs with submolecular resolution revealed several distinct molecular conformations which we attribute to different angular orientations of the rotator and which are locally stable states according to density functional theory calculations. Time-resolved tunneling current spectra showed that the rotator undergoes a torsional motion around the molecular long axis as stimulated by tunneling electrons in a one-electron process with an excitation energy threshold of 355 meV. Calculations identified an intrinsic axial vibration mode of the rotator group at 370 meV as adsorbed on the surface, which we propose to be the channel for effectively converting the tunneling electron energy into the mechanical energy of the intramolecular torsion.
authors: Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, China.
authors: Weihua
authors: W
authors: Wang
authors: Xingqiang
authors: X
authors: Shi
authors: Mochen
authors: M
authors: Jin
authors: Christian
authors: C
authors: Minot
authors: Michel A
authors: MA
authors: Van Hove
authors: Jean-Paul
authors: JP
authors: Collin
authors: Nian
authors: N
authors: Lin