title: Thiolate versus Selenolate: Structure, Stability, and Charge Transfer Properties.
abstract: Selenolate is considered as an alternative to thiolate to serve as a headgroup mediating the formation of self-assembled monolayers (SAMs) on coinage metal substrates. There are, however, ongoing vivid discussions regarding the advantages and disadvantages of these anchor groups, regarding, in particular, the energetics of the headgroup-substrate interface and their efficiency in terms of charge transport/transfer. Here we introduce a well-defined model system of 6-cyanonaphthalene-2-thiolate and -selenolate SAMs on Au(111) to resolve these controversies. The exact structural arrangements in both types of SAMs are somewhat different, suggesting a better SAM-building ability in the case of selenolates. At the same time, both types of SAMs have similar packing densities and molecular orientations. This permitted reliable competitive exchange and ion-beam-induced desorption experiments which provided unequivocal evidence for a stronger bonding of selenolates to the substrate as compared to the thiolates. Regardless of this difference, the dynamic charge transfer properties of the thiolate- and selenolate-based adsorbates were found to be nearly identical, as determined by the core-hole-clock approach, which is explained by a redistribution of electron density along the molecular framework, compensating the difference in the substrate-headgroup bond strength.
authors: †Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland.
authors: Jakub
authors: J
authors: Ossowski
authors: ‡Angewandte Physikalische Chemie, Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany.
authors: Tobias
authors: T
authors: Wächter
authors: §Institut für Anorganische und Analytische Chemie, Universität Frankfurt, Max-von-Laue-Straße 7, 60438 Frankfurt, Germany.
authors: Laura
authors: L
authors: Silies
authors: §Institut für Anorganische und Analytische Chemie, Universität Frankfurt, Max-von-Laue-Straße 7, 60438 Frankfurt, Germany.
authors: Martin
authors: M
authors: Kind
authors: †Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland.
authors: Agnieszka
authors: A
authors: Noworolska
authors: ∥Physikdepartment E20, Technische Universität München, 85747 Garching, Germany.
authors: Florian
authors: F
authors: Blobner
authors: †Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland.
authors: Dominika
authors: D
authors: Gnatek
authors: †Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland.
authors: Jakub
authors: J
authors: Rysz
authors: §Institut für Anorganische und Analytische Chemie, Universität Frankfurt, Max-von-Laue-Straße 7, 60438 Frankfurt, Germany.
authors: Michael
authors: M
authors: Bolte
authors: ∥Physikdepartment E20, Technische Universität München, 85747 Garching, Germany.
authors: Peter
authors: P
authors: Feulner
authors: §Institut für Anorganische und Analytische Chemie, Universität Frankfurt, Max-von-Laue-Straße 7, 60438 Frankfurt, Germany.
authors: Andreas
authors: A
authors: Terfort
authors: †Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland.
authors: Piotr
authors: P
authors: Cyganik
authors: ‡Angewandte Physikalische Chemie, Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany.
authors: Michael
authors: M
authors: Zharnikov
keywords: bond strength; charge transfer; metal surfaces; selenolate; self-assembled monolayers; self-assembly