Probing Charges on the Atomic Scale by Means of Atomic Force Microscopy

Albrecht, Florian; Repp, Jascha; Fleischmann, M.; Scheer, Manfred; Ondráček, Martin; Jelı́nek, Pavel

doi:10.1103/physrevlett.115.076101

Cited by 62 publications

(62 citation statements)

References 35 publications

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“…This is important to ensure that local variations of the tunneling current cannot influence the spectra indirectly via vertical displacements of the tip. The tip sample spacing is estimated from AFM data for CO functionalized tips and given in terms of center-to-center distance of the last tip atom the top-most metal layer of the sample [32]. In case of the Au adatoms on NaCl the tip sample spacing refers to the STM point contact between tip and metal sample.…”

Section: Methodsmentioning

confidence: 99%

“…They can be deliberately charged negatively [49], giving rise to a change in the KPFS signal [25]. Further, we used several molecular systems for benchmarking, the KPFS data of which we published recently in a different context [32]. One of these molecular systems is PTCDA adsorbed on Cu(111), which is known to reduce the work function of Cu(111) [50,51].…”

Section: Choice Of Systemsmentioning

confidence: 99%

“…To this end, for each lateral position on a dense grid a KPFS parabola f (V ) at a safe distance to avoid artifacts [32] and two I (z) curves at different voltages are recorded immediately one after another. Figure 2 shows exemplarily a set of these curves.…”

Section: Data Acquisitionmentioning

confidence: 99%

“…Kelvin probe force spectroscopy (KPFS) [21] is an established technique to reliably extract variations of the contact potential on the very local scale [22][23][24][25][26][27][28][29][30]-at least as long as the tip is far enough from the sample and not entering the regime of Pauli repulsion [31,32]. Further improvements of the interpretation and data acquisition of KPFS and related techniques are active fields of research, progressing fast at the moment [33][34][35][36][37].…”

Section: Introductionmentioning

confidence: 99%

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Local tunneling decay length and Kelvin probe force spectroscopy

et al. 2015

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In the past, current-distance spectroscopy has been widely applied to determine variations of the work function at surfaces. While for homogeneous sample areas this technique is commonly accepted to yield at least qualitative results, its applicability to atomic-scale variations has not been proven neither right nor wrong. Here we benchmark measurements of the current-distance decay constant against the well established Kelvin probe force spectroscopy for four distinctly different cases with atomic-scale variations of the local contact potential. The two techniques yield quite different results. Whereas the maps of the current-distance decay constant are consistent with being topographical artifacts, the Kelvin probe force spectroscopy maps show variations of the local contact potential difference in agreement with expected surface dipoles. This comparison clarifies that maps of the current-distance decay constant are not suited to directly characterize contact potential variations at surfaces on atomic length scales.

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Section: Methodsmentioning

confidence: 99%

Section: Choice Of Systemsmentioning

confidence: 99%

Section: Data Acquisitionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Local tunneling decay length and Kelvin probe force spectroscopy

et al. 2015

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“…It has been demonstrated that KPFM is able to reach the atomic [16][17][18]and sub molecular [19] resolution too. The straightforward interpretation in terms of local contact potential difference is no more possible at the atomic scale though [20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Charge-state dynamics in electrostatic force spectroscopy

Ondráček

Hapala²,

Jelı́nek³

2016

Nanotechnology

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We present a numerical model which allows us to study the Kelvin force probe microscopy response to the charge switching in quantum dots at various time scales. The model provides more insight into the behavior of frequency shift and dissipated energy under different scanning conditions measuring a temporarily charged quantum dot on surface. Namely, we analyze the dependence of the frequency shift, its fluctuation and of the dissipated energy, on the resonance frequency of tip and electron tunneling rates between tip-quantum dot and quantum dot-sample. We discuss two complementary approaches to simulating the charge dynamics, a stochastic and a deterministic one. In addition, we derive analytic formulas valid for small amplitudes, describing relations between the frequency shift, dissipated energy, and the characteristic rates driving the charging and discharging processes.

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Rasterkraftmikroskopie für die molekulare Strukturaufklärung

et al. 2018

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Mit der Rastersondenmikroskopie kann man auf einer Oberfläche adsorbierte Moleküle individuell und mit hoher Auflösung untersuchen. Die Technik, die bei tiefen Temperaturen und im Ultrahochvakuum durchgeführt wird, liefert Informationen über Struktur, Konfiguration, Ladungszustand, Aromatizität und die Beteiligung von Resonanzstrukturen. Durch Funktionalisierung der Spitze eines Rasterkraftmikroskops mit einem CO‐Molekül können Einzelmoleküle mit atomarer Auflösung abgebildet werden, ihre Adsorptionsgeometrie kann gemessen und die Bindungsordnungen im Molekül können bestimmt werden. Mit der Rastertunnelmikroskopie und der Kelvinsondenkraftmikroskopie kann man zudem die Elektronendichte der molekularen Grenzorbitale bzw. die Ladungsverteilung innerhalb des Moleküls kartieren. In Kombination ergeben diese Methoden ein hochauflösendes Verfahren zur Identifizierung und Charakterisierung von Einzelmolekülen. Die Empfindlichkeit auf Einzelmoleküle sowie die Option, durch Manipulation von Atomen mit der Spitze des Mikroskops chemische Reaktionen auszulösen, eröffnen einzigartige chemische Anwendungsmöglichkeiten und heben die Rastersondenmikroskopie von den klassischen Methoden zur molekularen Strukturaufklärung heraus. Somit kann die Rasterkraftmikroskopie nicht nur bei der Identifizierung von schwer zu bestimmenden Naturstoffen helfen, sondern sie ist auch ein leistungsstarkes und besonders gut geeignetes Instrument, um Oberflächenreaktionen zu untersuchen und Radikale und molekulare Mischungen zu charakterisieren. In diesem Aufsatz zeigen wir auf, welche Entwicklung die hochauflösende Rastersondenmikroskopie mit funktionalisierter Spitze bei der molekularen Strukturaufklärung und ‐charakterisierung in den vergangenen Jahren genommen hat, und erörtern die Herausforderungen der kommenden Jahre.

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Probing Charges on the Atomic Scale by Means of Atomic Force Microscopy

Cited by 62 publications

References 35 publications

Local tunneling decay length and Kelvin probe force spectroscopy

Local tunneling decay length and Kelvin probe force spectroscopy

Charge-state dynamics in electrostatic force spectroscopy

Rasterkraftmikroskopie für die molekulare Strukturaufklärung

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