Dynamik monodisperser Cluster unter dem schnellen Rastertunnelmikroskop
Zusammenfassung der Projektergebnisse
The project “Dynamics of monodisperse clusters under the fast scanning probe microscope” aimed at resolving the effects of temperature, adsorbates and ongoing reactions on the structural dynamics of atomically precise supported clusters. How fluctional are clusters, how do they sinter – and can we deduce from such findings concepts for stabilization? To that purpose, a scanning tunneling microscope (STM) has been accelerated to movie-rate image acquisition by addition of an external module, maintaining atomic resolution. Difficulties in this constant height measurement approach arise with cluster heights above two atomic layers. To overcome this intrinsic problem, we successfully implemented tracking algorithms that work under constant current conditions. These technological developments resulted in several scientific highlights. We started with following the ethene surface polymerization to graphene at moderate temperatures and found the surprising formation of size-specific coronene-like carbon cluster intermediates (consisting of 7 C6 rings). We succeeded in developing general concepts for cluster stabilization by systematically varying wetting and non-wetting sites on surfaces. We applied this concept to boron nitride films with known pore characteristics and managed to follow details on reversible cluster isomerization and diffusion in situ. While atoms diffuse along the rim of a pore, a small Pd~3 cluster experiences the corrugation in the potential energy landscape that leads to a discrepancy between adsorption site symmetry (sixfold – film) and jump dynamics symmetry (threefold – underlying support) which could clearly be revealed. We identified for clusters on graphene supports isomer-specific diffusivities, as well as isomer interconversion, and could follow the individual cluster diffusion path of a Pd12 cluster with atom tracking – clearly indicating a path that avoids non-wetting surface areas and connects the wetting ones. On studying these dynamics we realized that the dynamics of the support itself is essential for the complete understanding of these cluster-assembled materials. On one hand, we managed to investigate the Arrhenius-activated diffusion of hydrogen atoms on a magnetite (001) support, hereby revealing how the proximity to surface defects affects hopping rates. On the other hand, we discovered a new opportunity to apply our fast STM techniques: Instead of using single movie frames, averaging of several hundreds of images helps to reveal surface structures that persist under heavily dynamic adsorbate movements that make the single images appear fuzzy. In this way, we could demonstrate how the subsurface cation vacancy reconstruction of the magnetite support still exists as a local structural motif at the orderdisorder phase transition around 720 K. Summarizing, this project successfully pursued the defined research goals. We use this technology in a new proposal where we study cluster dynamics under defined reaction conditions in UHV systems. We are also heading for an application in air and liquid phase, by implementing the Fast STM technique in further microscopes; topic of a further DFG/DACH proposal.
Projektbezogene Publikationen (Auswahl)
- Au(111)-supported Platinum Nanoparticles: Ripening and Activity. MRS Advances 2 (8), 2017, 1-6
Wieghold, Sarah; Nienhaus, Lea; Siebel, Armin; Krause, Maximilian; Wand, Patricia; Gruebele, Martin; Heiz, Ueli; Esch, Friedrich
(Siehe online unter https://doi.org/10.1557/adv.2017.75) - Ethene to Graphene: Surface Catalyzed Chemical Pathways, Intermediates, and Assembly. J. Phys. Chem. C 121 (17), 2017, 9413-9423
Wang, Bo; König, Michael; Bromley, Catherine J.; Yoon, Bokwon; Treanor, Michael-John Treanor; Garrido Torres, José A.; Caffio, Marco; Grillo, Federico Grillo; Früchtl, Herbert; Richardson, Neville V.; Esch, Friedrich; Heiz, Ueli; Landmann, Uzi; Schaub, Renald
(Siehe online unter https://doi.org/10.1021/acs.jpcc.7b01999) - Plasmonic support-mediated activation of 1 nm platinum clusters for catalysis. Physical Chemistry Chemical Physics 19 (45), 2017, 30570-30577
Wieghold, Sarah; Nienhaus, Lea; Knoller, Fabian L.; Schweinberger, Florian F.; Shepherd, James J.; Lyding, Joseph W.; Heiz, Ueli; Gruebele, Martin; Esch, Friedrich
(Siehe online unter https://doi.org/10.1039/c7cp04882c) - A Microscopy Approach to Investigating the Energetics of Small Supported Metal Clusters. The Journal of Physical Chemistry C 122 (39), 2018, 22569-22576
Lechner, Barbara A. J.; Knoller, Fabian; Bourgund, Alexander; Heiz, Ueli; Esch, Friedrich
(Siehe online unter https://doi.org/10.1021/acs.jpcc.8b06866) - Influence of Local Defects on the Dynamics of O–H Bond Breaking and Formation on a Magnetite Surface. The Journal of Physical Chemistry C 123 (32), 2019, 19742-19747
Bourgund, Alexander; Lechner, Barbara A. J.; Meier, Matthias; Franchini, Cesare; Parkinson, Gareth S.; Heiz, Ueli; Esch, Friedrich
(Siehe online unter https://doi.org/10.1021/acs.jpcc.9b05547) - The new FAST module: A portable and transparent add-on module for time-resolved investigations with commercial scanning probe microscopes. Ultramicroscopy 205, 2019, 49-56
Dri, Carlo; Panighel, Mirco; Tiemann, Daniel; Patera, Laerte L.; Troiano, Giulia; Fukamori, Yves; Knoller, Fabian; Lechner, Barbara A.J.; Cautero, Giuseppe; Giuressi, Dario; Comelli, Giovanni; Fraxedas, Jordi; Africh, Cristina; Esch, Friedrich
(Siehe online unter https://doi.org/10.1016/j.ultramic.2019.05.010) - Order–disorder phase transition of the subsurface cation vacancy reconstruction on Fe3O4(001). Physical Chemistry Chemical Physics 22 (16), 2020, 8336-8343
Arndt, Björn; Lechner, Barbara A. J.; Bourgund, Alexander; Grånäs, Elin; Creutzburg, Marcus; Krausert, Konstantin; Hulva, Jan; Parkinson, Gareth S.; Schmid, Michael; Vonk, Vedran; Esch, Friedrich; Stierle, Andreas
(Siehe online unter https://doi.org/10.1039/d0cp00690d) - Cluster Catalysis with Lattice Oxygen: Tracing Oxygen Transport from a Magnetite (001) Support onto Small Pt Clusters. ACS Catalysis, 2021, 9519-9529
Kaiser, Sebastian; Maleki, Farahnaz; Zhang, Ke; Harbich, Wolfgang; Heiz, Ueli; Tosoni, Sergio; Lechner, Barbara A. J.; Pacchioni, Gianfranco; Esch, Friedrich
(Siehe online unter https://doi.org/10.1021/acscatal.1c01451)
