Positioning single atoms with a scanning tunnelling microscope
TL;DR: In this paper, Binnig and Rohrer used the scanning tunnelling microscope (STM) to position individual xenon atoms on a single-crystal nickel surface with atomic pre-cision.
Abstract: SINCE its invention in the early 1980s by Binnig and Rohrer1,2, the scanning tunnelling microscope (STM) has provided images of surfaces and adsorbed atoms and molecules with unprecedented resolution The STM has also been used to modify surfaces, for example by locally pinning molecules to a surface3 and by transfer of an atom from the STM tip to the surface4 Here we report the use of the STM at low temperatures (4 K) to position individual xenon atoms on a single-crystal nickel surface with atomic pre-cision This capacity has allowed us to fabricate rudimentary structures of our own design, atom by atom The processes we describe are in principle applicable to molecules also In view of the device-like characteristics reported for single atoms on surfaces5,6, the possibilities for perhaps the ultimate in device miniaturization are evident
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TL;DR: The most relevant features of WSXM, a freeware scanning probe microscopy software based on MS-Windows, are described and some relevant procedures of the software are carried out.
Abstract: In this work we briefly describe the most relevant features of WSXM, a freeware scanning probe microscopy software based on MS-Windows. The article is structured in three different sections: The introduction is a perspective on the importance of software on scanning probe microscopy. The second section is devoted to describe the general structure of the application; in this section the capabilities of WSXM to read third party files are stressed. Finally, a detailed discussion of some relevant procedures of the software is carried out.
6,996 citations
TL;DR: This work describes a simple method for folding long, single-stranded DNA molecules into arbitrary two-dimensional shapes, which can be programmed to bear complex patterns such as words and images on their surfaces.
Abstract: 'Bottom-up fabrication', which exploits the intrinsic properties of atoms and molecules to direct their self-organization, is widely used to make relatively simple nanostructures. A key goal for this approach is to create nanostructures of high complexity, matching that routinely achieved by 'top-down' methods. The self-assembly of DNA molecules provides an attractive route towards this goal. Here I describe a simple method for folding long, single-stranded DNA molecules into arbitrary two-dimensional shapes. The design for a desired shape is made by raster-filling the shape with a 7-kilobase single-stranded scaffold and by choosing over 200 short oligonucleotide 'staple strands' to hold the scaffold in place. Once synthesized and mixed, the staple and scaffold strands self-assemble in a single step. The resulting DNA structures are roughly 100 nm in diameter and approximate desired shapes such as squares, disks and five-pointed stars with a spatial resolution of 6 nm. Because each oligonucleotide can serve as a 6-nm pixel, the structures can be programmed to bear complex patterns such as words and images on their surfaces. Finally, individual DNA structures can be programmed to form larger assemblies, including extended periodic lattices and a hexamer of triangles (which constitutes a 30-megadalton molecular complex).
6,141 citations
Cites background from "Positioning single atoms with a sca..."
...These are (1) strand invasion, (2) an excess of staples, (3) cooperative effects and (4) design that intentionally does not rely on binding between staples....
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...But the widespread use of scaffolded self-assembly, and in particular the use of long DNA scaffolds in combination with hundreds of short strands, has been inhibited by several misconceptions: it was assumed that (1) sequencesmust be optimized(20) to avoid secondary structure or undesired binding interactions, (2) strands must be highly purified, and (3) strand concentrations must be precisely equimolar....
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Book•
01 Jul 2007
TL;DR: Barad, a theoretical physicist and feminist theorist, elaborates her theory of agential realism as mentioned in this paper, which is at once a new epistemology, ontology, and ethics.
Abstract: Meeting the Universe Halfway is an ambitious book with far-reaching implications for numerous fields in the natural sciences, social sciences, and humanities. In this volume, Karen Barad, theoretical physicist and feminist theorist, elaborates her theory of agential realism. Offering an account of the world as a whole rather than as composed of separate natural and social realms, agential realism is at once a new epistemology, ontology, and ethics. The starting point for Barad’s analysis is the philosophical framework of quantum physicist Niels Bohr. Barad extends and partially revises Bohr’s philosophical views in light of current scholarship in physics, science studies, and the philosophy of science as well as feminist, poststructuralist, and other critical social theories. In the process, she significantly reworks understandings of space, time, matter, causality, agency, subjectivity, and objectivity.
In an agential realist account, the world is made of entanglements of “social” and “natural” agencies, where the distinction between the two emerges out of specific intra-actions. Intra-activity is an inexhaustible dynamism that configures and reconfigures relations of space-time-matter. In explaining intra-activity, Barad reveals questions about how nature and culture interact and change over time to be fundamentally misguided. And she reframes understanding of the nature of scientific and political practices and their “interrelationship.” Thus she pays particular attention to the responsible practice of science, and she emphasizes changes in the understanding of political practices, critically reworking Judith Butler’s influential theory of performativity. Finally, Barad uses agential realism to produce a new interpretation of quantum physics, demonstrating that agential realism is more than a means of reflecting on science; it can be used to actually do science.
4,731 citations
TL;DR: This work presents an autonomous ordering and assembly of atoms and molecules on atomically well-defined surfaces that combines ease of fabrication with exquisite control over the shape, composition and mesoscale organization of the surface structures formed.
Abstract: The fabrication methods of the microelectronics industry have been refined to produce ever smaller devices, but will soon reach their fundamental limits. A promising alternative route to even smaller functional systems with nanometre dimensions is the autonomous ordering and assembly of atoms and molecules on atomically well-defined surfaces. This approach combines ease of fabrication with exquisite control over the shape, composition and mesoscale organization of the surface structures formed. Once the mechanisms controlling the self-ordering phenomena are fully understood, the self-assembly and growth processes can be steered to create a wide range of surface nanostructures from metallic, semiconducting and molecular materials.
2,013 citations
Cites background from "Positioning single atoms with a sca..."
...The decades since then have seen the invention of the scanning tunnelling microscope that allows us to image and manipulate individual molecules and atom...
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TL;DR: The most widely used technique for atomic-resolution force microscopy in vacuum is frequency-modulation AFM (FM-AFM), as well as other dynamic methods as discussed by the authors.
Abstract: This article reviews the progress of atomic force microscopy in ultrahigh vacuum, starting with its invention and covering most of the recent developments. Today, dynamic force microscopy allows us to image surfaces of conductors and insulators in vacuum with atomic resolution. The most widely used technique for atomic-resolution force microscopy in vacuum is frequency-modulation atomic force microscopy (FM-AFM). This technique, as well as other dynamic methods, is explained in detail in this article. In the last few years many groups have expanded the empirical knowledge and deepened our theoretical understanding of frequency-modulation atomic force microscopy. Consequently spatial resolution and ease of use have been increased dramatically. Vacuum atomic force microscopy opens up new classes of experiments, ranging from imaging of insulators with true atomic resolution to the measurement of forces between individual atoms.
1,948 citations
References
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IBM1
TL;DR: In this paper, surface microscopy using vacuum tunneling has been demonstrated for the first time, and topographic pictures of surfaces on an atomic scale have been obtained for CaIrSn 4 and Au.
Abstract: Surface microscopy using vacuum tunneling is demonstrated for the first time. Topographic pictures of surfaces on an atomic scale have been obtained. Examples of resolved monoatomic steps and surface reconstructions are shown for (110) surfaces of CaIrSn 4 and Au.
4,290 citations
TL;DR: In this article, the first successful tunneling experiment with an externally and reproducibly adjustable vacuum gap is reported, based on the exponential dependence of the tunneling resistance on the width of the gap.
Abstract: We report on the first successful tunneling experiment with an externally and reproducibly adjustable vacuum gap. The observation of vacuum tunneling is established by the exponential dependence of the tunneling resistance on the width of the gap. The experimental setup allows for simultaneous investigation and treatment of the tunnel electrode surfaces.
1,685 citations
TL;DR: In this paper, an atomic-scale modification of the surface of a nearly perfect germanium crystal, effected by the tungsten tip of a tunnelling microscope, was reported.
Abstract: The desire to modify materials on the smallest possible scale is motivated by goals ranging from high-density information storage to the purposeful transformation of genetic material. Here we report an atomic-scale modification of the surface of a nearly perfect germanium crystal, effected by the tungsten tip of a tunnelling microscope. We believe this to be the smallest spatially controlled, purposeful transformation yet impressed on matter and we argue that the limit set by the discreteness of atomic structure has now essentially been reached.
242 citations
IBM1
TL;DR: scanning tunneling microscopy and scanning tunneling spectroscopy are shown that the current-voltage characteristics of a diode configuration consisting of an STM tip over specific sites of a boron-exposed silicon(111) surface exhibit NDR.
Abstract: Negative differential resistance (NDR) is the essential property that allows fast switching in certain types of electronic devices. With scanning tunneling microscopy (STM) and scanning tunneling spectroscopy, it is shown that the current-voltage characteristics of a diode configuration consisting of an STM tip over specific sites of a boron-exposed silicon(111) surface exhibit NDR. These NDR-active sites are of atomic dimensions (∼1 nanometer). NDR in this case is the result of tunneling through localized, atomic-like states. Thus, desirable device characteristics can be obtained even on the atomic scale.
216 citations
IBM1
TL;DR: The accomplishment of the smallest yet, purposeful, spatially localized changes in matter, effected on a graphite surface is reported, believing that the changes result from the pinning of individual organic molecules to the graphite.
Abstract: In a very short time the scanning tunnelling microscope has become an important tool in surface science, and physics in general. Its primary use has been to obtain atomic-resolution images of surfaces, but recently, efforts have been made to use it to manipulate materials as well as image them. One may now reasonably ask if it is possible to move and alter matter predictably on an atomic scale. Here we report the accomplishment of the smallest yet, purposeful, spatially localized changes in matter, effected on a graphite surface. We believe that the changes result from the pinning of individual organic molecules to the graphite. The reverse manipulation, the removal of pinned molecules, has also been demonstrated. Finally, we have evidence that we can remove a portion of a pinned molecule, effectively performing transformations on single molecules using the tunnelling microscope.
167 citations