Relationship between the Structure and Electrical Conductivity of 12-Mer Single-Stranded Polyadenine Studied by Scanning Tunnelling Microscope

2019 ◽  
Vol 966 ◽  
pp. 119-125
Author(s):  
Harison Rozak ◽  
Wan Nurfadhilah Zaharim ◽  
Issei Miyazaki ◽  
Nur Eliana Ismail ◽  
Siti Nuramira Abu Bakar ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Current Mode ◽  
Chain Structure ◽  
Constant Current ◽  
Scanning Tunnelling Microscope ◽  
One Dimensional ◽  
Phosphate Backbone ◽  
Scanning Tunnelling ◽  
Tunnelling Microscopy ◽  
Fixed Bias

Abstract: In order to investigate the structure and electrical conductivity of (DNA), Scanning Tunnelling Microscopy (STM) studies were carried out on a model of DNA which was composed of a 12-mer single-stranded polyadenine connected via sugar-phosphate backbone. The 12-mer single-stranded polyadenine molecules were found to be aligned in parallel to each other at a separation 25±7.5 Å. This alignment formed a one-dimensional chain structure, which indicated that the side-by-side coupling among the molecules was strong. The STM measurements with constant current mode and fixed bias voltage, demonstrate that, the electrical conductivity of DNA bases could be deduced by monitoring the size of the structure of 12-mer single-stranded polyadenine.

scholarly journals Ni nanocrystals on HOPG(0001): A scanning tunnelling microscope study

2013 ◽  
Vol 4 ◽  
pp. 406-417 ◽  
Author(s):  
Michael Marz ◽  
Keisuke Sagisaka ◽  
Daisuke Fujita
Keyword(s):  
Surface Science ◽  
Crystal Formation ◽  
Scanning Tunnelling Microscope ◽  
Annealing Step ◽  
Cluster Shape ◽  
Scanning Tunnelling ◽  
Tunnelling Microscopy ◽  
Stepwise Annealing ◽  
Poster Presentations ◽  
Ni Clusters

The growth mode of small Ni clusters evaporated in UHV on HOPG has been investigated by scanning tunnelling microscopy. The size, the size distribution, and the shape of the clusters have been evaluated for different evaporation conditions and annealing temperatures. The total coverage of the surface strongly depends on the evaporation rate and time, whereas the influence of these parameters is low on the cluster size. Subsequent stepwise annealing has been performed. This results in a reduction of the total amount of the Ni clusters accompanied by a decreasing in the overall coverage of the surface. The diameter of the clusters appears to be less influenced by the annealing than is their height. Besides this, the cluster shape is strongly influenced, changing to a quasi-hexagonal geometry after the first annealing step, indicating single-crystal formation. Finally, a reproducible methodology for picking up individual clusters is reported Parts of this work have been presented as oral or poster presentations in several national and international conferences (Meeting of the Physical Society of Japan 2011 and 2012, 6th International Symposium on Surface Science 2012, and ImagineNano 2013)..

One-dimensional reactivity in catalysis studied with the scanning tunnelling microscope

Nature ◽  
1993 ◽  
Vol 363 (6431) ◽  
pp. 706-709 ◽  
Author(s):  
F. M. Leibsle ◽  
P. W. Murray ◽  
S. M. Francis ◽  
G. Thornton ◽  
M. Bowker
Keyword(s):  
Scanning Tunnelling Microscope ◽  
One Dimensional ◽  
Scanning Tunnelling

Se concentration dependent superstructure transformations of CuSe monolayer on Cu(111) substrate

2D Materials ◽  
2021 ◽  
Author(s):  
Gefei Niu ◽  
Jianchen Lu ◽  
Xingyue Wang ◽  
Zilin Ruan ◽  
Hui Zhang ◽  
...  
Keyword(s):  
Intermediate State ◽  
Lattice Mismatch ◽  
2D Materials ◽  
Honeycomb Structure ◽  
One Dimensional ◽  
The Past ◽  
Moire Pattern ◽  
Moiré Pattern ◽  
Scanning Tunnelling ◽  
Tunnelling Microscopy

Abstract As one of the most distinctive members of the monolayer transition metal monochalcogenides (TMM) family, the CuSe monolayer with a honeycomb structure has drawn much attention in the past few years. Depending on the Se concentration, the CuSe monolayer has two distinct superstructures on a Cu(111) substrate, a one dimensional (1D) moiré pattern, and two dimensional (2D) periodic nanopores. Here, we devise a strategy for simultaneous fabrication of the two superstructures of the CuSe monolayer on a Cu(111) substrate via artificially creating a density gradient of the Se concentration by an off-centered deposition method. At the boundary of the two superstructures, an intermediate state of the CuSe monolayer with a 2D hexagonal moiré pattern connected by six twisted petal-like stripes is observed. High-resolution scanning tunnelling microscopy characterizations of three distinct CuSe monolayer superstructures demonstrate that the Se density can effectively modulate the stress in the CuSe monolayer formed by the lattice mismatch, driving the superstructure transformation from 1D moiré pattern through 2D intermediate states to 2D periodic nanopores. In addition, scanning tunnelling spectroscopy measurements show that the intermediate state features a semiconducting behaviour with a band gap of ~ 2.0 eV. Our findings open up a new route for superstructure transformation control of 2D materials.

Imaging by Sliding Planes in Scanning Tunnelling Microscopy

1989 ◽  
Vol 159 ◽  
Author(s):  
John D. Todd ◽  
John B. Pethica
Keyword(s):  
Point Defects ◽  
Layered Materials ◽  
Atomic Scale ◽  
Single Atom ◽  
Scanning Tunnelling Microscope ◽  
Mechanical Contact ◽  
Conductance Fluctuations ◽  
Microscope Images ◽  
Scanning Tunnelling ◽  
Tunnelling Microscopy

ABSTRACTScanning tunnelling microscope images of layered materials in a non-uhv environment exhibit various anomalous phenomena, including enhanced corrugation heights, periodicity over large areas and a marked absence of point defects. We have modified a precision indentation device to allow STM rastering of a tip across a surface, while simultaneously monitoring mechanical contact. Images we have obtained from this apparatus on an HOPG sample exhibit atomic scale resolution with contact areas much larger than a single atom. Contrast in the image results from periodic conductance fluctuations as the layers of the sample undergo shear in the region of the tip. We provide a model for this process, which explains a variety of curious, and otherwise unrelated phenomena occurring during STM imaging of these materials.

Mechanical systems for a synchrotron X-ray-enhanced scanning tunnelling microscope

2010 ◽  
Vol 1 (MEDSI-6) ◽  
Author(s):  
C. Preissner ◽  
V. Rose ◽  
C. Pitts
Keyword(s):  
Vacuum Chamber ◽  
Prototype System ◽  
Scanning Tunnelling Microscope ◽  
X Ray ◽  
Scanning Tunnelling ◽  
Final Design ◽  
Tunnelling Microscopy ◽  
The Impact ◽  
Photon Source

Synchrotron X-ray-enhanced scanning tunnelling microscopy (SXSTM) is a novel technique by which materials can be studied with elemental-sensitive and nanometre-spatial resolution. This poster covers the mechanical engineering design for the prototype SXSTM instrument. System performance and sample handling requirements along with the desire to use existing components constrained the design. The SXSTM needs to be mechanically and acoustically isolated from the environment. In addition, all sample preparations are done in situ, and thus, the sample and SXSTM tips need to be prepared and moved inside the vacuum chamber with a wobble stick. The final design incorporates an Advanced Photon Source-designed vacuum chamber, existing components and commercial parts to provide the user with a robust prototype system to demonstrate the impact of this new technique.

An improved design for an Scanning Tunnelling Microscope (STM) for use in a Transmission Electron Microscope (TEM)

1991 ◽  
Vol 49 ◽  
pp. 384-385
Author(s):  
W.K. Lo ◽  
J.C.H. Spence
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Mechanical Stability ◽  
Scanning Tunnelling Microscope ◽  
Reflection Mode ◽  
Specimen Holder ◽  
Transmission Electron ◽  
Scanning Tunnelling ◽  
Improved Design

An improved design for a combination Scanning Tunnelling Microscope/TEM specimen holder is presented. It is based on earlier versions which have been used to test the usefulness of such a device. As with the earlier versions, this holder is meant to replace the standard double-tilt specimen holder of an unmodified Philips 400T TEM. It allows the sample to be imaged simultaneously by both the STM and the TEM when the TEM is operated in the reflection mode (see figure 1).The resolution of a STM is determined by its tip radii as well as its stability. This places strict limitations on the mechanical stability of the tip with respect to the sample. In this STM the piezoelectric tube scanner is rigidly mounted inside the endcap of the STM holder. The tip coarse approach to the sample (z-direction) is provided by an Inchworm which is located outside the TEM vacuum.

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.

On-Surface Radical Oligomerisation: A New Approach to STM Tip-Induced Reactions

2018 ◽  
Author(s):  
Gaolei Zhan ◽  
Younes Makoudi ◽  
Judicael Jeannoutot ◽  
Simon Lamare ◽  
Michel Féron ◽  
...  
Keyword(s):  
Sample Surface ◽  
Scanning Tunnelling Microscope ◽  
Transfer Event ◽  
New Approach ◽  
The Past ◽  
Organic Nanostructures ◽  
Scanning Tunnelling ◽  
New Strategy ◽  
Surface Fabrication ◽  
And Control

Over the past decade, on-surface fabrication of organic nanostructures has been widely investigated for the development of molecular electronic devices, nanomachines, and new materials. Here, we introduce a new strategy to obtain alkyl oligomers in a controlled manner using on-surface radical oligomerisations that are triggered by the electrons/holes between the sample surface and the tip of a scanning tunnelling microscope. The resulting radical-mediated mechanism is substantiated by a detailed theoretical study. This electron transfer event only occurs when <i>V</i><sub>s</sub> < -3 V or <i>V</i><sub>s</sub> > + 3 V and allows access to reactive radical species under exceptionally mild conditions. This transfer can effectively ‘switch on’ a sequence leading to formation of oligomers of defined size distribution due to the on-surface confinement of reactive species. Our approach enables new ways to initiate and control radical oligomerisations with tunnelling electrons, leading to molecularly precise nanofabrication.

Single-charge transport through hybrid core–shell Au-ZnS quantum dots: a comprehensive analysis from a modified energy structure

Nanoscale ◽  
2021 ◽  
Author(s):  
Tuhin Shuvra Basu ◽  
Simon Diesch ◽  
Ryoma Hayakawa ◽  
Yutaka Wakayama ◽  
Elke Scheer
Keyword(s):  
Quantum Dots ◽  
Electronic Structure ◽  
Carrier Transport ◽  
Comprehensive Analysis ◽  
Energy Structure ◽  
Core Shell ◽  
Single Charge ◽  
Scanning Tunnelling Microscope ◽  
Single Carrier ◽  
Scanning Tunnelling

We examined the modified electronic structure and single-carrier transport of individual hybrid core–shell metal–semiconductor Au-ZnS quantum dots using a scanning tunnelling microscope.

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