scholarly journals Intermolecular vs molecule–substrate interactions: A combined STM and theoretical study of supramolecular phases on graphene/Ru(0001)

2011 ◽  
Vol 2 ◽  
pp. 365-373 ◽  
Author(s):  
Michael Roos ◽  
Benedikt Uhl ◽  
Daniela Künzel ◽  
Harry E Hoster ◽  
Axel Groß ◽  
...  
Keyword(s):  
Intermolecular Interactions ◽  
Graphene Layer ◽  
Organic Molecules ◽  
Theoretical Study ◽  
Adsorption Potential ◽  
Scanning Tunnelling ◽  
Tunnelling Microscopy ◽  
Lateral Variations ◽  
Tetracarboxylic Dianhydride ◽  
Theoretical Results

The competition between intermolecular interactions and long-range lateral variations in the substrate–adsorbate interaction was studied by scanning tunnelling microscopy (STM) and force field based calculations, by comparing the phase formation of (sub-) monolayers of the organic molecules (i) 2-phenyl-4,6-bis(6-(pyridin-3-yl)-4-(pyridin-3-yl)pyridin-2-yl)pyrimidine (3,3'-BTP) and (ii) 3,4,9,10-perylene tetracarboxylic-dianhydride (PTCDA) on graphene/Ru(0001). For PTCDA adsorption, a 2D adlayer phase was formed, which extended over large areas, while for 3,3'-BTP adsorption linear or ring like structures were formed, which exclusively populated the areas between the maxima of the moiré structure of the buckled graphene layer. The consequences for the competing intermolecular interactions and corrugation in the adsorption potential are discussed and compared with the theoretical results.

scholarly journals Optical absorption signature of a self-assembled dye monolayer on graphene

2016 ◽  
Vol 7 ◽  
pp. 862-868 ◽  
Author(s):  
Tessnim Sghaier ◽  
Sylvain Le Liepvre ◽  
Céline Fiorini ◽  
Ludovic Douillard ◽  
Fabrice Charra
Keyword(s):  
Cross Section ◽  
Surface Density ◽  
Graphene Layer ◽  
Absorption Cross ◽  
Transparent Substrate ◽  
Resonant Interactions ◽  
Scanning Tunnelling ◽  
Tunnelling Microscopy ◽  
Free Molecules ◽  
Oriented Parallel

A well-organized monolayer of alkylated perylene-3,4,9,10-tetracarboxylic-3,4,9,10-diimide (PTCDI) has been formed onto CVD graphene transferred on a transparent substrate. Its structure has been probed by scanning tunnelling microscopy and its optical properties by polarized transmission spectroscopy at varying incidence. The results show that the transition dipoles of adsorbed PTCDI are all oriented parallel to the substrate. The maximum absorption is consistent with the measured surface density of molecules and their absorption cross section. The spectrum presents mainly a large red-shift of the absorption line compared with the free molecules dispersed in solution, whereas the relative strengths of the vibronic structures are preserved. These changes are attributed to non-resonant interactions with the graphene layer and the neighbouring molecules.

scholarly journals Transformations of PTCDA structures on rutile TiO2 induced by thermal annealing and intermolecular forces

2015 ◽  
Vol 6 ◽  
pp. 1498-1507 ◽  
Author(s):  
Szymon Godlewski ◽  
Jakub S Prauzner-Bechcicki ◽  
Thilo Glatzel ◽  
Ernst Meyer ◽  
Marek Szymoński
Keyword(s):  
Low Temperature ◽  
Thermal Annealing ◽  
Intermolecular Forces ◽  
Molecular Structures ◽  
Additional Energy ◽  
Ordered Structures ◽  
Scanning Tunnelling ◽  
Tunnelling Microscopy ◽  
Temperature Scanning ◽  
Tetracarboxylic Dianhydride

Transformations of molecular structures formed by perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) molecules on a rutile TiO2(110) surface are studied with low-temperature scanning tunnelling microscopy. We demonstrate that metastable molecular assemblies transform into differently ordered structures either due to additional energy provided by thermal annealing or when the influence of intermolecular forces is increased by the enlarged amount of deposited molecules. Proper adjustment of molecular coverage and substrate temperature during deposition allows for fabrication of desired assemblies. Differences between PTCDA/TiO2(110) and PTCDA/TiO2(011) systems obtained through identical experimental procedures are discussed.

scholarly journals Theoretical study of carbon-based tips for scanning tunnelling microscopy

2016 ◽  
Vol 27 (10) ◽  
pp. 105201 ◽  
Author(s):  
C González ◽  
E Abad ◽  
Y J Dappe ◽  
J C Cuevas
Keyword(s):  
Theoretical Study ◽  
Scanning Tunnelling Microscopy ◽  
Scanning Tunnelling ◽  
Tunnelling Microscopy ◽  
Carbon Based

scholarly journals PTCDA adsorption on CaF2 thin films

2020 ◽  
Vol 11 ◽  
pp. 1615-1622
Author(s):  
Philipp Rahe
Keyword(s):  
Thin Films ◽  
Density Functional ◽  
Interface Layer ◽  
Molecular Electronic ◽  
Functional Theory ◽  
Atomic Size ◽  
Insulating Films ◽  
Scanning Tunnelling ◽  
Tunnelling Microscopy ◽  
Tetracarboxylic Dianhydride

Thin insulating films are commonly employed for the electronic decoupling of molecules as they enable a preservation of the intrinsic molecular electronic functionality. Here, the molecular properties of 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) adsorbed on insulating CaF2 thin films that were grown on Si(111) surfaces are studied. Scanning tunnelling microscopy is used to compare the properties of PTCDA molecules adsorbed on a partly CaF1-covered Si(111) surface with deposition on thicker CaF2/CaF1/Si(111) films. The identification of mostly single molecules on the CaF1/Si(111) interface layer is explained by the presence of atomic-size defects within this layer. Geometry-optimisation calculations using density functional theory reveal a geometry on CaF2(111) of nearly flat-lying PTCDA molecules with two oxygen atoms displaced towards calcium surface ions. This geometry is in agreement with the experimental observations.

An Improved Method for the Preparation and TEM Examination of Sharp Pointed Tips used in APFIM and STM

1990 ◽  
Vol 48 (2) ◽  
pp. 102-103
Author(s):  
E.A. Fischione ◽  
P.E. Fischione ◽  
J.J. Haugh ◽  
M.G. Burke
Keyword(s):  
Atom Probe ◽  
Preparation Process ◽  
Improved Method ◽  
Ion Milling ◽  
Polishing Process ◽  
Probe Field ◽  
Scanning Tunnelling ◽  
Stm Tips ◽  
Tunnelling Microscopy ◽  
Ion Microscopy

A common requirement for both Atom Probe Field-Ion Microscopy (APFIM) and Scanning Tunnelling Microscopy (STM) is a sharp pointed tip for use as either the specimen (APFIM) or the probe (STM). Traditionally, tips have been prepared by either chemical or electropolishing techniques. Recently, ion-milling has been successfully employed in the production of APFIM tips [1]. Conventional electropolishing techniques are applicable to a wide variety of metals, but generally require careful manual adjustments during the polishing process and may also be time-consuming. In order to reduce the time and effort involved in the preparation process, a compact, self-contained polishing unit has been developed. This system is based upon the conventional two-stage electropolishing technique in which the specimen/tip blank is first locally thinned or “necked”, and subsequently electropolished until separation occurs.[2,3] The result of this process is the production of two APFIM or STM tips. A mechanized polishing unit that provides these functions while automatically maintaining alignment has been designed and developed.

scholarly journals Combined quantum tunnelling and dielectrophoretic trapping for molecular analysis at ultra-low analyte concentrations

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Longhua Tang ◽  
Binoy Paulose Nadappuram ◽  
Paolo Cadinu ◽  
Zhiyu Zhao ◽  
Liang Xue ◽  
...  
Keyword(s):  
Limited Range ◽  
Practical Implementation ◽  
Successful Operation ◽  
Detection Rates ◽  
Quantum Tunnelling ◽  
Conductive Substrate ◽  
Scanning Tunnelling ◽  
Tunnelling Microscopy ◽  
Transport Molecules ◽  
Magnitude Increase

AbstractQuantum tunnelling offers a unique opportunity to study nanoscale objects with atomic resolution using electrical readout. However, practical implementation is impeded by the lack of simple, stable probes, that are required for successful operation. Existing platforms offer low throughput and operate in a limited range of analyte concentrations, as there is no active control to transport molecules to the sensor. We report on a standalone tunnelling probe based on double-barrelled capillary nanoelectrodes that do not require a conductive substrate to operate unlike other techniques, such as scanning tunnelling microscopy. These probes can be used to efficiently operate in solution environments and detect single molecules, including mononucleotides, oligonucleotides, and proteins. The probes are simple to fabricate, exhibit remarkable stability, and can be combined with dielectrophoretic trapping, enabling active analyte transport to the tunnelling sensor. The latter allows for up to 5-orders of magnitude increase in event detection rates and sub-femtomolar sensitivity.

Insights into electrocatalysis by scanning tunnelling microscopy

2021 ◽  
Author(s):  
Xiang Wang ◽  
Yu-Qi Wang ◽  
Ya-Chen Feng ◽  
Dong Wang ◽  
Li-Jun Wan
Keyword(s):  
Scanning Tunnelling Microscopy ◽  
Surface Processes ◽  
Scanning Tunnelling ◽  
Tunnelling Microscopy ◽  
Electrocatalytic Reactions

This review summarizes the applications of scanning tunnelling microscopy in electrocatalysis, including the investigation of the electrocatalyst structures and the surface processes related to electrocatalytic reactions.

scholarly journals Investigation of single-domain Au silicide nanowires on Si(110) formed for Au coverages in the monolayer regime

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Stephan Appelfeller
Keyword(s):  
Fermi Level ◽  
Surface Structure ◽  
Density Of States ◽  
The Self ◽  
Single Domain ◽  
Photoemission Spectroscopy ◽  
Annealing Temperatures ◽  
Self Organized ◽  
Scanning Tunnelling ◽  
Tunnelling Microscopy

AbstractThe self-organized formation of single domain Au silicide nanowires is observed on Si(110). These nanowires are analysed using scanning tunnelling microscopy (STM) and spectroscopy (STS) as well as photoemission spectroscopy (PES). Core-level PES is utilised to confirm the formation of Au silicide and establish its presence as the top most surface structure, i.e., the nanowires. The growth of the Au silicide nanowires and their dimensions are studied by STM. They form for Au coverages of about 1 monolayer and are characterized by widths of about 2 to 3 nm and heights below 1 nm while reaching lengths exceeding 500 nm when choosing appropriate annealing temperatures. Valence band PES and STS indicate a small but finite density of states at the Fermi level typical for compound metals.

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