<i>In-situ</i> characterization of O-terminated Cu tips for high-resolution atomic force microscopy

Liebig, Alexander; Giessibl, Franz J.

doi:10.1063/1.5085747

Cited by 16 publications

(12 citation statements)

References 38 publications

(68 reference statements)

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“…1 d,g, respectively. At small tip-sample distances, the CO-CO interaction results in a bright, circularly-symmetric feature in constant-height AFM images 3 , 42 . The two COFI images are equal, which confirms that the atomic composition of the tip apex did not change during the measurement on (111) (see Supplementary Fig.…”

Section: Resultsmentioning

confidence: 99%

Quantifying the evolution of atomic interaction of a complex surface with a functionalized atomic force microscopy tip

Liebig

Hapala

Weymouth

et al. 2020

Sci Rep

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terminating the tip of an atomic force microscope with a co molecule allows data to be acquired with a well-known and inert apex. Previous studies have shown conflicting results regarding the electrostatic interaction, indicating in some cases that the negative charge at the apex of the co dominates, whereas in other cases the positive charge at the end of the metal tip dominates. to clarify this, we investigated CaF 2 (111). CaF 2 is an ionic crystal and the (111) surface does not possess charge inversion symmetry. far from the surface, the interaction is dominated by electrostatics via the negative charge at the apex. closer to the surface, pauli repulsion and co bending dominate, which leads to an unexpected appearance of the complex 3-atom unit cell. We compare simulated data in which the electrostatics are modeled by point particles versus a charge density calculated by Dft. We also compare modeling pauli repulsion via individual Lennard-Jones potentials versus a total charge density overlap. In doing so, we determine forcefield parameters useful for future investigations of biochemical processes.

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Section: Resultsmentioning

confidence: 99%

Quantifying the evolution of atomic interaction of a complex surface with a functionalized atomic force microscopy tip

Liebig

Hapala

Weymouth

et al. 2020

Sci Rep

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“…Gross et al discovered the great utility of CO terminated tips in a pioneering experiment on atomic imaging of pentacene [ 54 ] displayed in Figure 12 . Although other inert tip terminations such as noble gases [ 55 ] and Cu oxide tips [ 56 , 57 , 58 ] have been studied, CO tip terminations are still popular in spite of their lateral softness [ 59 ] as emphasized in a recent review by Gross et al [ 60 ].…”

Section: Resultsmentioning

confidence: 99%

Probing the Nature of Chemical Bonds by Atomic Force Microscopy

Giessibl¹

2021

Molecules

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The nature of the chemical bond is important in all natural sciences, ranging from biology to chemistry, physics and materials science. The atomic force microscope (AFM) allows to put a single chemical bond on the test bench, probing its strength and angular dependence. We review experimental AFM data, covering precise studies of van-der-Waals-, covalent-, ionic-, metallic- and hydrogen bonds as well as bonds between artificial and natural atoms. Further, we discuss some of the density functional theory calculations that are related to the experimental studies of the chemical bonds. A description of frequency modulation AFM, the most precise AFM method, discusses some of the experimental challenges in measuring bonding forces. In frequency modulation AFM, forces between the tip of an oscillating cantilever change its frequency. Initially, cantilevers were made mainly from silicon. Most of the high precision measurements of bonding strengths by AFM became possible with a technology transfer from the quartz watch technology to AFM by using quartz-based cantilevers (“qPlus force sensors”), briefly described here.

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“…The CO‐pickup was observed as a change in the STM contrast of the surface CO molecules, which were then imaged as dark spots with bright protrusions at the center. [ 18,38 ]…”

Section: Methodsmentioning

confidence: 99%

“…[ 30,32,35–37 ] Recently, O‐terminated copper tips (CuOx‐tips) have emerged as an alternative form of tip functionalization. [ 29–31,38 ] Here, the terminal oxygen atom is covalently bonded to the adjacent Cu atoms in a tetrahedral configuration. This leads to a considerably higher rigidity of this tip allowing to significantly reduce the related imaging artifacts.…”

Section: Introductionmentioning

confidence: 99%

Mechanical and Chemical Interactions in Atomically Defined Contacts

Yesilpinar

Lammers

Timmer

et al. 2021

Small

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Providing fundamental insights in atomic interactions, dedicated methods in atomic force microscopy allow measuring the threshold forces needed to move single adsorbed atoms or molecules. However, the chemical and structural properties of the probe‐tip can drastically influence the results. Establishing atomically defined contacts in such experiments, the tips in the present study are functionalized with various chemically and structurally different terminations. Xenon atoms are moved along an atomically defined metal/metal‐oxide boundary where all tips show a pulling mechanism and slight force variations, which are assigned to polarization effects within the tip‐sample junction. Detaching Xe atoms from the boundary involves a significantly higher energy barrier where chemical reactive Cu‐tips cause Xe pickup before any lateral manipulation. Passivating the tip by inert probe particles (Xe or CO) allows further approaching the surface Xe atom. Yet, the small vertical attraction and pronounced tip relaxations prevent reaching sufficient threshold forces inducing manipulation. In contrast, the high structural rigidity of oxygen‐terminated Cu‐tips allows manipulations even beyond the threshold where they evolve from initial pulling, via sliding to pushing mode. The detailed quantitative analysis of the processes in the atomically defined junctions emphasizes the mechanical and chemical interactions for highly controlled experiments with piconewton sensitivity.

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In-situ characterization of O-terminated Cu tips for high-resolution atomic force microscopy

Cited by 16 publications

References 38 publications

Quantifying the evolution of atomic interaction of a complex surface with a functionalized atomic force microscopy tip

Quantifying the evolution of atomic interaction of a complex surface with a functionalized atomic force microscopy tip

Probing the Nature of Chemical Bonds by Atomic Force Microscopy

Mechanical and Chemical Interactions in Atomically Defined Contacts

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