Obtaining Detailed Structural Information about Supramolecular Systems on Surfaces by Combining High-Resolution Force Microscopy with <i>ab Initio</i> Calculations

Kawai, Shigeki; Sadeghi, Ali; Xu, Feng; Peng, Lifen; Pawlak, Rémy; Glatzel, Thilo; Willand, Alexander; Orita, Akihiro; Otera, Junzo; Goedecker, Stefan; Meyer, Ernst

doi:10.1021/nn403672m

Cited by 57 publications

(59 citation statements)

References 55 publications

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“…The sharp ridges observed in the intramolecular region often mimics the internal molecular structure [5], with only few exceptions [6,7]. The capability of AFM/STM to resolve internal atomic and chemical structure in real space opened new horizons for the characterization of molecules and surfaces [5,[8][9][10][11][12][13][14][15] at atomic scale.The origin of high resolution of molecular structures in AFM has been attributed to Pauli repulsion [2,16] and the bending of the functionalized tip apex [5]. Recently, we introduced a numerical model [7] which provides a unified insight into the detailed mechanism of the high resolution imaging with decorated tips in both AFM and STM.…”

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Origin of High-Resolution IETS-STM Images of Organic Molecules with Functionalized Tips

et al. 2014

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Recently, the family of high-resolution scanning probe imaging techniques using decorated tips has been complimented by a method based on inelastic electron tunneling spectroscopy (IETS). The new technique resolves the inner structure of organic molecules by mapping the vibrational energy of a single carbonmonoxide (CO) molecule positioned at the apex of a scanning tunnelling microscope (STM) tip. Here, we explain high-resolution IETS imaging by extending the model developed earlier for STM and atomic force microscopy (AFM) imaging with decorated tips. In particular, we show that the tip decorated with CO acts as a nanoscale sensor that changes the energy of the CO frustrated translation in response to the change of the local curvature of the surface potential. In addition, we show that high resolution AFM, STM and IETS-STM images can deliver information about intramolecular charge transfer for molecules deposited on a surface. To demonstrate this, we extended our numerical model by taking into the account the electrostatic force acting between the decorated tip and surface Hartree potential.PACS numbers: 68.37. Ef, 68.37.Ps, 68.43.Fg One of the most exciting and significant breakthroughs in field of scanning probe microscopy (SPM) in last years is undoubtedly the achievement of high-resolution STM [1] and AFM [2] images of molecular structures with functionalized tips [3,4]. In general, the high-resolution images, being typically acquired in the regime where the tip-surface interaction becomes repulsive, are characterized by a presence of sharp features in both intra and intermolecular regions. The sharp ridges observed in the intramolecular region often mimics the internal molecular structure [5], with only few exceptions [6,7]. The capability of AFM/STM to resolve internal atomic and chemical structure in real space opened new horizons for the characterization of molecules and surfaces [5,[8][9][10][11][12][13][14][15] at atomic scale.The origin of high resolution of molecular structures in AFM has been attributed to Pauli repulsion [2,16] and the bending of the functionalized tip apex [5]. Recently, we introduced a numerical model [7] which provides a unified insight into the detailed mechanism of the high resolution imaging with decorated tips in both AFM and STM. According to the model, the decorated tip apex acts as an atomistic force sensor that responds with significant relaxations of the decorating particle (probe particle) towards local minima of the tip-sample interaction potential at close distances. The relaxations cause discontinuities in both the frequency shift and the tunneling current signals and thus become observable in AFM and STM images as sharp contrast features. Although the model was originally used to confirm the decisive role of Pauli repulsion in the high-resolution STM and AFM imaging of molecular structures done with functionalized tips, it must be noted that imaging of other types of interactions (e.g. electrostatic) should also be possible [5]. Namely, the influence of intramo...

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Origin of High-Resolution IETS-STM Images of Organic Molecules with Functionalized Tips

et al. 2014

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“…The AFM-derived technique of Kelvin probe force spectroscopy 41 can be used to map out the electrostatic potential in front of a surface. [42][43][44][45][46][47][48] In the case of single molecules, it can be used to map out their quadrupole moment, 49 the charge distribution inside molecules, 50 or the polarity of bonds. 51 a) Electronic mail: liu@dcb.unibe.ch b) Electronic mail: jascha.repp@ur.de Such charge mapping has been shown to be sensitive enough to detect charging of individual atoms by a single electron.…”

Section: General Introductionmentioning

confidence: 99%

Forces from periodic charging of adsorbed molecules

Kocić

Decurtins

Liu

et al. 2017

The Journal of Chemical Physics

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In a recent publication [Kocić et al., Nano Lett. 15, 4406 (2015)], it was shown that gating of molecular levels in the field of an oscillating tip of an atomic force microscope can enable a periodic charging of individual molecules synchronized to the tip’s oscillatory motion. Here we discuss further implications of such measurements, namely, how the force difference associated with the single-electron charging manifests itself in atomic force microscopy images and how it can be detected as a function of tip-sample distance. Moreover, we discuss how the critical voltage for the charge-state transition depends on distance and how that relates to the local contact potential difference. These measurements allow also for an estimate of the absolute tip-sample distance.

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“…For example, atomic resolution with chemical sensitivity was demonstrated using force-distance spectroscopy [4]. Using the force-voltage spectroscopy mode for Kelvin probe force microscopy (KPFM), charge states of single atoms [5], defects [6], and molecules [7] were determined, and submolecular resolution was obtained [8][9][10]. The atomic contrast observed with KPFM [11][12][13][14][15] triggered efforts to explain the underlying contrast mechanism theoretically [16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Investigating atomic contrast in atomic force microscopy and Kelvin probe force microscopy on ionic systems using functionalized tips

et al. 2014

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Noncontact atomic force microscopy (NC-AFM) and Kelvin probe force microscopy (KPFM) have become important tools for nanotechnology; however, their contrast mechanisms on the atomic scale are not entirely understood. Here we used chlorine vacancies in NaCl bilayers on Cu(111) as a model system to investigate atomic contrast as a function of applied voltage, tip height, and tip functionalization. We demonstrate that the AFM contrast on the atomic scale decisively depends on both the tip termination and the sample voltage. On the contrary, the local contact potential difference (LCPD) acquired with KPFM showed the same qualitative contrast for all tip terminations investigated, which resembled the contrast of the electric field of the sample. We find that the AFM contrast stems mainly from electrostatic interactions but its tip dependence cannot be explained by the tip dipole alone. With the aid of a simple electrostatic model and by density functional theory we investigate the underlying contrast mechanisms.

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Obtaining Detailed Structural Information about Supramolecular Systems on Surfaces by Combining High-Resolution Force Microscopy with ab Initio Calculations

Cited by 57 publications

References 55 publications

Origin of High-Resolution IETS-STM Images of Organic Molecules with Functionalized Tips

Origin of High-Resolution IETS-STM Images of Organic Molecules with Functionalized Tips

Forces from periodic charging of adsorbed molecules

Investigating atomic contrast in atomic force microscopy and Kelvin probe force microscopy on ionic systems using functionalized tips

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