1
|
Tamtögl A, Sacchi M, Schwab V, Koza MM, Fouquet P. Molecular motion of a nanoscopic moonlander via translations and rotations of triphenylphosphine on graphite. Commun Chem 2024; 7:78. [PMID: 38582953 PMCID: PMC10998885 DOI: 10.1038/s42004-024-01158-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 03/22/2024] [Indexed: 04/08/2024] Open
Abstract
Mass transport at surfaces determines the kinetics of processes such as heterogeneous catalysis and thin-film growth, with the diffusivity being controlled by excitation across a translational barrier. Here, we use neutron spectroscopy to follow the nanoscopic motion of triphenylphosphine (P(C6H5)3 or PPh3) adsorbed on exfoliated graphite. Together with force-field molecular dynamics simulations, we show that the motion is similar to that of a molecular motor, i.e. PPh3 rolls over the surface with an almost negligible activation energy for rotations and motion of the phenyl groups and a comparably small activation energy for translation. While rotations and intramolecular motion dominate up to about 300 K, the molecules follow an additional translational jump-motion across the surface from 350-500 K. The unique behaviour of PPh3 is due to its three-point binding with the surface: Along with van der Waals corrected density functional theory calculations, we illustrate that the adsorption energy of PPh3 increases considerably compared to molecules with flat adsorption geometry, yet the effective diffusion barrier for translational motion increases only slightly. We rationalise these results in terms of molecular symmetry, structure and contact angle, illustrating that the molecular degrees of freedom in larger molecules are intimately connected with the diffusivity.
Collapse
Affiliation(s)
- Anton Tamtögl
- Institute of Experimental Physics, Graz University of Technology, Graz, Austria.
| | - Marco Sacchi
- Department of Chemistry, University of Surrey, GU2 7XH, Guildford, UK
| | - Victoria Schwab
- Institute of Experimental Physics, Graz University of Technology, Graz, Austria
| | - Michael M Koza
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38000, Grenoble, France
| | - Peter Fouquet
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38000, Grenoble, France
| |
Collapse
|
2
|
Sabik A, Ellis J, Hedgeland H, Ward DJ, Jardine AP, Allison W, Antczak G, Tamtögl A. Single-molecular diffusivity and long jumps of large organic molecules: CoPc on Ag(100). Front Chem 2024; 12:1355350. [PMID: 38380395 PMCID: PMC10876995 DOI: 10.3389/fchem.2024.1355350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 01/15/2024] [Indexed: 02/22/2024] Open
Abstract
Energy dissipation and the transfer rate of adsorbed molecules do not only determine the rates of chemical reactions but are also a key factor that often dictates the growth of organic thin films. Here, we present a study of the surface dynamical motion of cobalt phthalocyanine (CoPc) on Ag(100) in reciprocal space based on the helium spin-echo technique in comparison with previous scanning tunnelling microscopy studies. It is found that the activation energy for lateral diffusion changes from 150 meV at 45-50 K to ≈100 meV at 250-350 K, and that the process goes from exclusively single jumps at low temperatures to predominantly long jumps at high temperatures. We thus illustrate that while the general diffusion mechanism remains similar, upon comparing the diffusion process over widely divergent time scales, indeed different jump distributions and a decrease of the effective diffusion barrier are found. Hence a precise molecular-level understanding of dynamical processes and thin film formation requires following the dynamics over the entire temperature scale relevant to the process. Furthermore, we determine the diffusion coefficient and the atomic-scale friction of CoPc and establish that the molecular motion on Ag(100) corresponds to a low friction scenario as a consequence of the additional molecular degrees of freedom.
Collapse
Affiliation(s)
- Agata Sabik
- Institute of Experimental Physics, University of Wrocław, Wrocław, Poland
- Department of Semiconductor Materials Engineering, Wrocław University of Science and Technology, Wrocław, Poland
| | - John Ellis
- Cavendish Laboratory, Cambridge, United Kingdom
| | | | | | | | | | - Grażyna Antczak
- Institute of Experimental Physics, University of Wrocław, Wrocław, Poland
| | - Anton Tamtögl
- Institute of Experimental Physics, Graz University of Technology, Graz, Austria
| |
Collapse
|
3
|
Salamon D, Bukvišová K, Jan V, Potoček M, Čechal J. Superflux of an organic adlayer towards its local reactive immobilization. Commun Chem 2023; 6:225. [PMID: 37853226 PMCID: PMC10584841 DOI: 10.1038/s42004-023-01020-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 10/02/2023] [Indexed: 10/20/2023] Open
Abstract
On-surface mass transport is the key process determining the kinetics and dynamics of on-surface reactions, including the formation of nanostructures, catalysis, or surface cleaning. Volatile organic compounds (VOC) localized on a majority of surfaces dramatically change their properties and act as reactants in many surface reactions. However, the fundamental question "How far and how fast can the molecules travel on the surface to react?" remains open. Here we show that isoprene, the natural VOC, can travel ~1 μm s-1, i.e., centimeters per day, quickly filling low-concentration areas if they become locally depleted. We show that VOC have high surface adhesion on ceramic surfaces and simultaneously high mobility providing a steady flow of resource material for focused electron beam synthesis, which is applicable also on rough or porous surfaces. Our work established the mass transport of reactants on solid surfaces and explored a route for nanofabrication using the natural VOC layer.
Collapse
Affiliation(s)
- David Salamon
- CEITEC - Central European Institute of Technology, Brno University of Technology, Purkyňova 123, 612 00, Brno, Czech Republic.
| | - Kristýna Bukvišová
- CEITEC - Central European Institute of Technology, Brno University of Technology, Purkyňova 123, 612 00, Brno, Czech Republic
| | - Vít Jan
- Fakulty of Mechanical Engineering, Brno University of Technology, Technická 2896/2, 616 69, Brno, Czech Republic
| | - Michal Potoček
- CEITEC - Central European Institute of Technology, Brno University of Technology, Purkyňova 123, 612 00, Brno, Czech Republic
| | - Jan Čechal
- CEITEC - Central European Institute of Technology, Brno University of Technology, Purkyňova 123, 612 00, Brno, Czech Republic.
- Fakulty of Mechanical Engineering, Brno University of Technology, Technická 2896/2, 616 69, Brno, Czech Republic.
| |
Collapse
|
4
|
Brooks A, Jenkins SJ, Wrabetz S, McGregor J, Sacchi M. The dehydrogenation of butane on metal-free graphene. J Colloid Interface Sci 2022; 619:377-387. [DOI: 10.1016/j.jcis.2022.03.128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Revised: 03/21/2022] [Accepted: 03/27/2022] [Indexed: 10/18/2022]
|
5
|
Chadwick H, Alkoby Y, Cantin JT, Lindebaum D, Godsi O, Maniv T, Alexandrowicz G. Molecular spin echoes; multiple magnetic coherences in molecule surface scattering experiments. Phys Chem Chem Phys 2021; 23:7673-7681. [PMID: 33331356 DOI: 10.1039/d0cp05399f] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In this paper we demonstrate that a molecular beam of hydrogen molecules can be magnetically manipulated to produce multiple coherences in the molecular interference pattern. Unlike spin 1/2 magnetic beam experiments, i.e., neutron and helium spin echo, the nuclear and rotational magnetic moments in a molecule are strongly coupled. We show experimentally and theoretically that this coupling leads to multiple magnetic field conditions under which the magnetic moment of molecules travelling with different speeds can be coherently refocussed. We also demonstrate that these multiple coherence signals are extremely sensitive to the scattering event, opening up new possibilities for measuring molecule-surface interactions.
Collapse
Affiliation(s)
- Helen Chadwick
- Department of Chemistry, College of Science, Swansea University, Swansea, SA2 8PP, UK.
| | | | | | | | | | | | | |
Collapse
|
6
|
Holst B, Alexandrowicz G, Avidor N, Benedek G, Bracco G, Ernst WE, Farías D, Jardine AP, Lefmann K, Manson JR, Marquardt R, Artés SM, Sibener SJ, Wells JW, Tamtögl A, Allison W. Material properties particularly suited to be measured with helium scattering: selected examples from 2D materials, van der Waals heterostructures, glassy materials, catalytic substrates, topological insulators and superconducting radio frequency materials. Phys Chem Chem Phys 2021; 23:7653-7672. [PMID: 33625410 DOI: 10.1039/d0cp05833e] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Helium Atom Scattering (HAS) and Helium Spin-Echo scattering (HeSE), together helium scattering, are well established, but non-commercial surface science techniques. They are characterised by the beam inertness and very low beam energy (<0.1 eV) which allows essentially all materials and adsorbates, including fragile and/or insulating materials and light adsorbates such as hydrogen to be investigated on the atomic scale. At present there only exist an estimated less than 15 helium and helium spin-echo scattering instruments in total, spread across the world. This means that up till now the techniques have not been readily available for a broad scientific community. Efforts are ongoing to change this by establishing a central helium scattering facility, possibly in connection with a neutron or synchrotron facility. In this context it is important to clarify what information can be obtained from helium scattering that cannot be obtained with other surface science techniques. Here we present a non-exclusive overview of a range of material properties particularly suited to be measured with helium scattering: (i) high precision, direct measurements of bending rigidity and substrate coupling strength of a range of 2D materials and van der Waals heterostructures as a function of temperature, (ii) direct measurements of the electron-phonon coupling constant λ exclusively in the low energy range (<0.1 eV, tuneable) for 2D materials and van der Waals heterostructures (iii) direct measurements of the surface boson peak in glassy materials, (iv) aspects of polymer chain surface dynamics under nano-confinement (v) certain aspects of nanoscale surface topography, (vi) central properties of surface dynamics and surface diffusion of adsorbates (HeSE) and (vii) two specific science case examples - topological insulators and superconducting radio frequency materials, illustrating how combined HAS and HeSE are necessary to understand the properties of quantum materials. The paper finishes with (viii) examples of molecular surface scattering experiments and other atom surface scattering experiments which can be performed using HAS and HeSE instruments.
Collapse
Affiliation(s)
- Bodil Holst
- Department of Physics and Technology, University of Bergen, Allegaten 55, 5007 Bergen, Norway.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Miletic M, Palczynski K, Dzubiella J. Quantifying entropic barriers in single-molecule surface diffusion. J Chem Phys 2020; 153:164713. [PMID: 33138417 DOI: 10.1063/5.0024178] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The quantitative role of entropy in the surface diffusion of molecules with many degrees of freedom is still not well understood. Here, we quantify entropic diffusion barriers as well as attempt frequencies by performing a systematic decomposition of the Arrhenius equation for single oligophenyl molecules of various lengths (two to six phenyl rings and benzene as the reference) on an amorphous silica surface using extensive molecular dynamics simulations. Attempt frequencies evaluated from velocity auto-correlation functions are found close to kBT/h, the frequency factor of transition state theory. Importantly, we find large positive entropy contributions to the free energy barrier of diffusion up to 55%, increasing with molecular length with 4.1 kJ/mol/phenyl ring. The entropic barrier is about 40%-60% of the entropy of the molecule surface adsorption free energy, revealing that at the transition states, the molecules can liberate a major part of their conformational states, increasing with length. The substantial role of the internal degrees of freedom for the diffusive dynamics is explicitly demonstrated by studying internally constrained, "rigid" version of the molecules. Finally, we discuss also rotational diffusion and the role of surface vibrations. Our results affirm that it is essential for quantitative studies and interpretation of surface diffusion of complex molecules to consider internal entropic effects.
Collapse
Affiliation(s)
- Mila Miletic
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
| | - Karol Palczynski
- Research Group for Simulations of Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109 Berlin, Germany
| | - Joachim Dzubiella
- Research Group for Simulations of Energy Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109 Berlin, Germany
| |
Collapse
|
8
|
Sacchi M, Singh P, Chisnall DM, Ward DJ, Jardine AP, Allison W, Ellis J, Hedgeland H. The dynamics of benzene on Cu(111): a combined helium spin echo and dispersion-corrected DFT study into the diffusion of physisorbed aromatics on metal surfaces. Faraday Discuss 2017; 204:471-485. [PMID: 28766630 PMCID: PMC5779075 DOI: 10.1039/c7fd00095b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We use helium spin-echo spectroscopy (HeSE) to investigate the dynamics of the diffusion of benzene adsorbed on Cu(111). The results of these measurements show that benzene moves on the surface through an activated jump-diffusion process between the adsorption sites on a Bravais lattice. Density Functional Theory (DFT) calculations with van der Waals (vdW) corrections help us understand that the molecule diffuses by jumping through non-degenerate hollow sites. The results of the calculations shed light on the nature of the binding interaction between this prototypical aromatic molecule and the metallic surface. The highly accurate HeSE experimental data provide a quantitatively stringent benchmark for the vdW correction schemes applied to the DFT calculations and we compare the performances of several dispersion interaction schemes.
Collapse
Affiliation(s)
- M Sacchi
- Department of Chemistry, University of Surrey, Guildford, GU2 7XH, UK.
| | | | | | | | | | | | | | | |
Collapse
|