Electron-Induced Switching Processes of Phthalocyanine Molecules on (?3??3) Bi/Ag(111)R30?: Tautomerization Accompanied by Rotation

We investigated single deprotonated phthalocyanine molecules (HPc) on ( 3 x 3 )Bi/Ag(111)R30 degrees by means of scanning tunneling microscopy (STM). Atomic-resolution topographic data reveal that the HPc adsorbs flat on top of a Bi atom. At sufficient bias voltage, STM-induced rotation and tautomerization of the HPc molecule are observed. Current-and bias voltage-dependent studies show that both processes are triggered via the molecule's N-H stretching mode by a single electron. A constant ratio between the tautomerization and the rotation rate is observed, corroborating that both processes originate from the same stimulus. Furthermore, molecular nanoprobe (MONA) experiments provide insight into the ballistic charge transport properties of the ( 3 x 3 )Bi/Ag(111) R30 degrees substrate. A distance-dependent study shows that the excitation rate decays with similar to d-1, indicating that ballistic transport mainly proceeds via the substrate's surface state. Direction-dependent MONA measurements reveal that the HPc molecule exhibits two different faces with distinct excitation probabilities.

Automated summary

We investigated the behavior of single deprotonated phthalocyanine molecules (HPc) on a (3x3)Bi/Ag(111) R30 degrees surface using scanning tunneling microscopy (STM). We observed the flat adsorption of HPc on a Bi atom and observed the rotation and tautomerization of the molecule under bias voltage. Further studies showed that both processes were triggered by the molecule's N-H stretching mode. MONA experiments provided insight into the ballistic charge transport properties of the substrate and revealed two different faces of the HPc molecule with distinct excitation probabilities.