SKM 2023 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 22: Poster Session: Organic Molecules on Inorganic Substrates I
O 22.1: Poster
Montag, 27. März 2023, 18:00–20:00, P2/EG
Charge-state lifetimes of single molecules on ultrathin insulating films — •Katharina Kaiser1, 3, Leonard-Alexander Lieske1, Jascha Repp2, and Leo Gross1 — 1IBM Research - Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland — 2Department of Physics, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany — 3Present address: Institut de Physique et de Chimie des Matériaux de Strasbourg, Département Surfaces et Interfaces, 23 Rue du Loess, BP 43, 67034 Strasbourg, France
In scanning tunneling microscopy (STM) experiments of molecules on insulating films, tunneling through molecular resonances goes along with transiently charging the molecule. The transition back to its charge ground state by tunneling through the insulating film crucially determines the charging dynamics of the system and with this is essential for understanding, e.g., excited state formation and luminescence quenching in electroluminescence experiments. The two quantities describing these processes are the average charging and discharging time, the latter being the lifetime of the charged state, and they are accessible in STM: By approaching the tip to the molecule at resonant tunnel conditions up to a regime where charge transport is limited by tunneling through the NaCl film the saturation of the tunnel current, which is a direct measure of the molecule's chargestate lifetime and thus provides a means to study charge and exciton dynamics, can be measured. We report on the chargestate lifetimes of individual molecules adsorbed on NaCl films of different thicknesses on Cu(111) and Au(111), and provide insights into the role of the substrate and the spacer layer.