Unidirectional Adsorbate Motion on a High-Symmetry Surface: “Walking” Molecules Can Stay the Course

Kwon, Ki‐Young; Wong, Kin; Pawin, Greg; Bartels, Ludwig; Stolbov, Sergey; Rahman, Talat S.

doi:10.1103/physrevlett.95.166101

Cited by 94 publications

(112 citation statements)

References 18 publications

(15 reference statements)

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“…Note that diffusion measurements by STM found in literature are typically carried out at tunnelling resistances in the range of 1-10 GO. 33,[47][48][49]64 Since the tunnel resistance in the experiments by Buchner et al 34 is even higher, i.e., the tip-substrate interaction is lower, a significant influence of the STM measurement on the thermally induced diffusion can be practically ruled out. In addition, no influence upon changing image size, scanning speed and the fast scan direction (vertical/horizontal) was reported.…”

Section: Diffusion and Rotation Of 2htppmentioning

confidence: 99%

Studying the dynamic behaviour of porphyrins as prototype functional molecules by scanning tunnelling microscopy close to room temperature

Marbach

Steinrück

2014

Chem. Commun.

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Scanning tunnelling microscopy (STM) enables us to directly observe the dynamic behaviour of organic molecules on surfaces. While imaging atoms and molecules using STM is certainly fascinating by itself, corresponding temperature-dependent measurements allow for the quantitative determination of the energetics and kinetics of the underlying molecular surface processes. Herein, we review recent advances in the STM investigation of the dynamic behaviour of adsorbed porphyrins at and close to room temperature.Three different case studies are discussed, providing insight into the dynamics of diffusion, rotation, reaction, and molecular switching at surfaces, based on isothermal STM measurements. The reviewed examples demonstrate that variable temperature STM can be a suitable tool to directly monitor the dynamic behaviour of individual adsorbed molecules, at and close to room temperature. Free base porphyrins on Cu(111) proved to be particularly suitable for these studies due to the strong bonding interaction between the iminic nitrogen atoms in the porphyrin macrocycle and the Cu substrate atoms. As a consequence, the corresponding activation energies for surface diffusion, self-metalation reaction and conformational switching are of a magnitude that allows for monitoring the processes at and around room temperature, in contrast to most previous studies, which were performed at cryogenic temperatures. The kinetic analysis of the surface diffusion and self-metalation was performed using an Arrhenius approach, yielding the corresponding activation energies and preexponential factors. In contrast, the conformational switching process was analysed in the framework of transition state theory, based on the Eyring equation. This approach provides a more detailed insight into interpretable thermodynamic potentials, i.e., the enthalpic and entropic contributions to the activation barrier. The analysis shows that at room temperature the adsorption and switching behaviour of the investigated free base porphyrin on Cu(111) is dominated by entropic effects. Since the entropic energy contribution vanishes at low temperatures, the importance of experiments conducted at temperatures close to room temperature is emphasized.

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Section: Diffusion and Rotation Of 2htppmentioning

confidence: 99%

Studying the dynamic behaviour of porphyrins as prototype functional molecules by scanning tunnelling microscopy close to room temperature

Marbach

Steinrück

2014

Chem. Commun.

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“…Figure 1 shows an STM image of DCA on Cu(111) and a simulation of the adsorption site (adsite) using density functional theory (DFT) on a 5 5 3 unit cell of substrate atoms. While the adsite of DCA resembles that of its oxygen [3] and sulfur [4] counterparts (anthraquinone and 9,10-dithioanthracene, respectively), DCA does not diffuse in a uniaxial fashion on Cu(111) and it also does not show more facile lateral manipulation along any particular substrate direction. Even at 90 K DCA retains sufficient surface mobility to assemble in patterns or to reach step edges.…”

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confidence: 91%

A Surface Coordination Network Based on Substrate‐Derived Metal Adatoms with Local Charge Excess

et al. 2008

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In the quest for increased control and tuneability of organic patterns at metal surfaces, more and more systems emerge that rely upon coordination of metal adatoms by organic ligands using endgroups such as carbonitriles, amines, and carboxylic acids.[1] Such systems promise great flexibility in the size and geometry of the surface pattern through choice of the ligand shape, the number and arrangement of ligating endgroups, and the nature of the metal centers. Planar (trigonal or square) arrangements of ligands around metal centers occur most commonly as a result of attractive interactions of the ligands with the substrate. In contrast, in the solution phase planar, and in particular trigonal planar, arrangements are quite rare and generally require ligands whose nature (for example bidentate, pincer shape) forces planarity.Given the relatively short history of the field of surface coordination chemistry, compared to its solution-phase counterpart, it is of great interest to know which information can be gleaned from the latter to predict that for the former.

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“…[15][16][17][18][19][20][21][22][23][24][25] For short n alkanes on a model Pt͑111͒ surface Raut and Fichthorn obtain directional anisotropy by molecular orientation. 17 Kwon et al 23 observed unidirectional diffusion of 9,10-dithioanthracene molecules on Cu͑111͒ in a combined scanning tunneling microscopy and density-functional theory ͑DFT͒ study. The thermally activated motion of these molecules, which form two S-Cu bonds, consists of subsequent hops of either one of the thiol groups.…”

Section: Introductionmentioning

confidence: 98%

Diffusion of 1,4-butanedithiol onAu(100)−(1×1): A DFT-based master-equation approach

Franke

Pehlke

2010

Phys. Rev. B

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The functionalization of metal surfaces via thiol-bonded molecules and the assembly of nanodevices on the surfaces should profit from a detailed atomistic understanding of the binding and diffusion properties. These differ substantially from the in-depth investigated situation of single adatoms. We report density-functional calculations for the elementary diffusion steps of 1,4-butanedithiol radicals ͑BDTRs͒ adsorbed on a Au͑100͒-͑1 ϫ 1͒ surface. The elementary diffusion steps are then combined into a description of the diffusion mechanism on long-time scales by integrating a master equation. The two S-Au bonds cause a multivalley potential-energy surface, which implies a complex diffusion mechanism. We identify the effect of the geometry constraints imposed by the ͑CH 2 ͒ 4 backbone on binding and diffusion. To this purpose we compare to the diffusion of a single SCH 3 radical on the same Au͑100͒-͑1 ϫ 1͒ surface. Altogether, the motion of the BDTR is walkinglike with the S-atoms crossing bridge sites of the Au surface one after the other. The lowest density-functional theory-Perdew and Wang 91 energy barrier for translation is 0.35 eV while the energy barrier for rotation comes out larger, 0.43 eV. As a result of this difference there will be correlations between subsequent diffusive displacements of the molecule. The isotropic diffusion constant on long-time scales is computed and the numerical results follow an Arrhenius law.

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Unidirectional Adsorbate Motion on a High-Symmetry Surface: “Walking” Molecules Can Stay the Course

Cited by 94 publications

References 18 publications

Studying the dynamic behaviour of porphyrins as prototype functional molecules by scanning tunnelling microscopy close to room temperature

Studying the dynamic behaviour of porphyrins as prototype functional molecules by scanning tunnelling microscopy close to room temperature

A Surface Coordination Network Based on Substrate‐Derived Metal Adatoms with Local Charge Excess

Diffusion of 1,4-butanedithiol onAu(100)−(1×1): A DFT-based master-equation approach

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