Molecular Symmetry Governs Surface Diffusion

Sonnleitner, Tobias; Swart, Ingmar; Pavliček, Niko; Pöllmann, Andreas; Repp, Jascha

doi:10.1103/physrevlett.107.186103

Cited by 22 publications

(29 citation statements)

References 22 publications

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“…Finally, concerning the effect of the substrate on the molecular symmetry, we would like to mention that a strong experimental sensitivity to molecular symmetry has been proven for derivatives of CuPc molecules on thin insulating films (see Ref. 40), suggesting that an almost-complete decoupling of the molecular states is indeed a good approximation for these systems.…”

Section: Discussionmentioning

confidence: 99%

Topographical fingerprints of many-body interference in STM junctions on thin insulating films

et al. 2012

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Negative differential conductance is a nonlinear transport phenomenon ubiquitous in molecular nanojunctions. Its physical origin can be the most diverse. In rotationally symmetric molecules with orbitally degenerate many-body states it can be ascribed to interference effects. We establish in this paper a criterion to identify the interference blocking scenario by correlating the spectral and the topographical information achievable in a scanning tunneling microscopy (STM) single-molecule measurement. Simulations of current-voltage characteristics as well as constant-height and constant-current STM images for a Cu-phthalocyanine on a thin insulating film are presented as experimentally relevant examples.

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Section: Discussionmentioning

confidence: 99%

Topographical fingerprints of many-body interference in STM junctions on thin insulating films

et al. 2012

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“…By means of inelastic excitations [23,24] it is possible to induce the lateral motion of individual molecules, as well as to switch between the two species. The results are presented in Fig.…”

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confidence: 99%

Atomic Force Microscopy Reveals Bistable Configurations of Dibenzo[a,h]thianthrene and their Interconversion Pathway

et al. 2012

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We investigated dibenzo [a,h]thianthrene molecules adsorbed on ultrathin layers of NaCl using a combined low-temperature scanning tunneling and atomic force microscope. Two stable configurations exist corresponding to different isomers of free nonplanar molecules. By means of excitations from inelastic electron tunneling we can switch between both configurations. Atomic force microscopy with submolecular resolution allows unambiguous determination of the molecular geometry, and the pathway of the interconversion of the isomers. Our investigations also shed new light on contrast mechanisms in scanning tunneling microscopy. DOI: 10.1103/PhysRevLett.108.086101 PACS numbers: 68.43.Fg, 68.37.Ef, 68.37.Ps, 82.37.Gk Recently, the chemical structure of a pentacene molecule has been visualized by means of noncontact atomic force microscopy (AFM) [1]. Shortly after, this method assisted in identifying the structure of an organic molecule [2]. In conjunction with the capability of scanning tunneling microscopy (STM) to perform orbital imaging on ultrathin insulating films [3], it is possible to gain independent and complementary information of the molecular as well as of the adsorption geometry, but also of the electronic structure of individual molecules.Unambiguous identification of configurational changes of adsorbed molecules is a challenging task by means of STM alone [4], probing the local density of states rather than geometry. Usually, additional techniques such as nearedge x-ray adsorption fine structure measurements have to be employed [5,6].In this Letter, we present combined STM and AFM experiments of dibenzo[a,h]thianthrene (DBTH) molecules adsorbed on ultrathin layers of sodium chloride. We demonstrate controlled switching between two different molecular configurations by means of inelastic excitations. AFM images with submolecular resolution directly reveal the configurational changes. Stereochemistry could be utilized to determine their interconversion pathway in detail.All AFM measurements were carried out in a homebuilt combined STM and AFM operating in an ultrahigh vacuum (p < 10 À10 mbar) at T ¼ 5 K. The AFM, based on the qPlus tuning fork design (spring constant k 0 % 1:8 Â 10 3 N m À1 , resonance frequency f 0 ¼ 26 057 Hz, quality factor Q % 10 4 ) [7], was operated in the frequency modulation mode [8]. Sub-Å ngstrom oscillation amplitudes have been used to maximize the lateral resolution [9]. Some of the STM measurements ( Figs. 1 and 2) were performed in a similar modified commercial STM from SPS-CreaTec. The bias voltage V was applied to the sample.Sodium chloride was evaporated onto clean Cu(111) single crystals at sample temperatures of about 280 K [10]. All experiments were carried out on a double layer, and we denote this substrate system as NaClð2MLÞ= Cuð111Þ. The DBTH molecules were synthesized as described previously [11].Low coverages of CO (for tip functionalization) and DBTH molecules were adsorbed at sample temperatures below 10 K. Following a recently developed technique, the tip ha...

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“…Diffusion of the molecules can be determined by comparing STM images acquired before and after a specified time interval and measuring the lateral displacement of the molecules. 15,29 In addition, a control molecule, NanoRoadster control (NC; Fig. 1d), which is structurally similar to NR but without a motor unit has been synthesised.…”

Section: Resultsmentioning

confidence: 99%

Light-Induced Translation of Motorized Molecules on a Surface

et al. 2016

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Molecular machines are a key component in the vision of molecular nanotechnology, and have the potential to transport molecular species and cargo on surfaces. The motion of such machines should be triggered remotely, ultimately allowing a large number of molecules to be propelled by a single source, with light being an attractive stimulus. Here, we report upon the photo-induced translation of molecular machines across a surface by characterizing single molecules before and after illumination. Illumination of molecules containing a motor unit results in an enhancement in the diffusion of the molecules. The effect vanishes if an incompatible photon energy is used or if the motor unit is removed from the molecule, revealing that the enhanced motion is due to the presence of the wavelength-sensitive motor in each molecule.Molecular machines with internal motors are fascinating objects that transform energy into useful motion at the nanoscale. [1][2][3][4][5][6] In nature many processes depend on molecular motors that perform specific mechanical tasks in living cells, 7 a prototypical process is the directional motion of myosin. 8 Several synthetic molecular motors have been synthesized, 2,9,10 including a molecular motor developed by Feringa and co-workers that rotates at a frequency in the MHz regime. [11][12][13][14] For ultimate control of molecular machines it is essential that the motor exhibits only one sense of rotation, resulting in unidirectional translation of the molecular machine on a surface, thus only forward and no backward motion, in contrast to random motion in all directions. 2 For synthetic molecular machines to contribute to the vision of nanotechnology by transporting molecular species and cargo on surfaces, the motion of

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Molecular Symmetry Governs Surface Diffusion

Cited by 22 publications

References 22 publications

Topographical fingerprints of many-body interference in STM junctions on thin insulating films

Topographical fingerprints of many-body interference in STM junctions on thin insulating films

Atomic Force Microscopy Reveals Bistable Configurations of Dibenzo[a,h]thianthrene and their Interconversion Pathway

Light-Induced Translation of Motorized Molecules on a Surface

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