title: Hot Carrier-Induced Tautomerization within a Single Porphycene Molecule on Cu(111).
abstract: Here, we report the study of tautomerization within a single porphycene molecule adsorbed on a Cu(111) surface using low-temperature scanning tunneling microscopy (STM) at 5 K. While molecules are adsorbed on the surface exclusively in the thermodynamically stable trans tautomer after deposition, a voltage pulse from the STM can induce the unidirectional trans → cis and reversible cis ↔ cis tautomerization. From the voltage and current dependence of the tautomerization yield (rate), it is revealed that the process is induced by vibrational excitation via inelastic electron tunneling. However, the metastable cis molecules are thermally switched back to the trans tautomer by heating the surface up to 30 K. Furthermore, we have found that the unidirectional tautomerization can be remotely controlled at a distance from the STM tip. By analyzing the nonlocal process in dependence on various experimental parameters, a hot carrier-mediated mechanism is identified, in which hot electrons (holes) generated by the STM travel along the surface and induce the tautomerization through inelastic scattering with a molecule. The bias voltage and coverage dependent rate of the nonlocal tautomerization clearly show a significant contribution of the Cu(111) surface state to the hot carrier-induced process.
authors.affiliation: †Department of Physical Chemistry, Fritz-Haber Institute of the Max-Planck Society, Faradayweg 4-6, 14195 Berlin, Germany.
authors.forename: Janina N
authors.initials: JN
authors.lastname: Ladenthin
authors.affiliation: †Department of Physical Chemistry, Fritz-Haber Institute of the Max-Planck Society, Faradayweg 4-6, 14195 Berlin, Germany.|‡Department of Physical Chemistry, University of Graz, Heinrichstrasse 28, 8010 Graz, Austria.
authors.forename: Leonhard
authors.initials: L
authors.lastname: Grill
authors.affiliation: §Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, Warsaw 01-224, Poland.
authors.forename: Sylwester
authors.initials: S
authors.lastname: Gawinkowski
authors.affiliation: †Department of Physical Chemistry, Fritz-Haber Institute of the Max-Planck Society, Faradayweg 4-6, 14195 Berlin, Germany.
authors.forename: Shuyi
authors.initials: S
authors.lastname: Liu
authors.affiliation: §Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, Warsaw 01-224, Poland.
authors.forename: Jacek
authors.initials: J
authors.lastname: Waluk
authors.affiliation: †Department of Physical Chemistry, Fritz-Haber Institute of the Max-Planck Society, Faradayweg 4-6, 14195 Berlin, Germany.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kumagai
keywords: hot carrier transport; metal surface; nonlocal adsorbate reaction; scanning tunneling microscopy; single molecule; tautomerization