title: Imaging the dynamics of individually adsorbed molecules.
abstract: Although noise is observed in many experiments, it is rarely used as a source of information. However, valuable information can be extracted from noisy signals. The motion of particles on a surface induced, for example, by thermal activation or by the interaction with the tip of a scanning tunnelling microscope may lead to fluctuations or switching of the tunnelling current. The analysis of these processes gives insight into dynamics on a single atomic or molecular level. Unfortunately, scanning tunnelling microscopy (STM) is not a useful tool to study dynamics in detail, as it is an intrinsically slow technique. Here, we show that this problem can be solved by providing a full real-time characterization of random telegraph noise in the current signal. The hopping rate, the noise amplitude and the relative occupation of the involved states are measured as a function of the tunnelling parameters, providing spatially resolved maps. In contrast to standard STM, our technique gives access to transiently populated states revealing an electron-driven hindered rotation between the equilibrium and two metastable positions of an individually adsorbed molecule. The new approach yields a complete characterization of copper phthalocyanine molecules on Cu(111), ranging from dynamical processes on surfaces to the underlying electronic structure on the single-molecule level.
authors.affiliation: Faculty of Physics and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, Duisburg, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Schaffert
authors.forename: Maren C
authors.initials: MC
authors.lastname: Cottin
authors.forename: Andreas
authors.initials: A
authors.lastname: Sonntag
authors.forename: Hatice
authors.initials: H
authors.lastname: Karacuban
authors.forename: Christian A
authors.initials: CA
authors.lastname: Bobisch
authors.forename: Nicolás
authors.initials: N
authors.lastname: Lorente
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Gauyacq
authors.forename: Rolf
authors.initials: R
authors.lastname: Möller