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An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a higher resolving power than light microscopes and can reveal the structure of smaller objects. A scanning transmission electron microscope has achieved better than 50 pm resolution in annular dark-field imaging mode and magnifications of up to about 10,000,000× whereas most light microscopes are limited by diffraction to about 200 nm resolution and useful magnifications below 2000×.
Nanotechnology is manipulation of matter on an atomic, molecular, and supramolecular scale. The earliest, widespread description of nanotechnology referred to the particular technological goal of precisely manipulating atoms and molecules for fabrication of macroscale products, also now referred to as molecular nanotechnology. A more generalized description of nanotechnology was subsequently established by the National Nanotechnology Initiative, which defined nanotechnology as the manipulation of matter with at least one dimension sized from 1 to 100 nanometers. This definition reflects the fact that quantum mechanical effects are important at this quantum-realm scale, and so the definition shifted from a particular technological goal to a research category inclusive of all types of research and technologies that deal with the special properties of matter which occur below the given size threshold. It is therefore common to see the plural form "nanotechnologies" as well as "nanoscale technologies" to refer to the broad range of research and applications whose common trait is size.
A scanning tunneling microscope (STM) is an instrument for imaging surfaces at the atomic level. Its development in 1981 earned its inventors, Gerd Binnig and Heinrich Rohrer, the Nobel Prize in Physics in 1986. For an STM, good resolution is considered to be 0.1 nm lateral resolution and 0.01 nm depth resolution. With this resolution, individual atoms within materials are routinely imaged and manipulated. The STM can be used not only in ultra-high vacuum but also in air, water, and various other liquid or gas ambients, and at temperatures ranging from near zero kelvin to over 1000 °C.
Atomic force microscopy (AFM) or scanning force microscopy (SFM) is a very-high-resolution type of scanning probe microscopy (SPM), with demonstrated resolution on the order of fractions of a nanometer, more than 1000 times better than the optical diffraction limit.
Mechanosynthesis is a term for hypothetical chemical syntheses in which reaction outcomes are determined by the use of mechanical constraints to direct reactive molecules to specific molecular sites. There are presently no non-biological chemical syntheses which achieve this aim. Some atomic placement has been achieved with scanning tunnelling microscopes.
Scanning probe microscope (SPM) is a branch of microscopy that forms images of surfaces using a physical probe that scans the specimen. SPM was founded in 1981, with the invention of the scanning tunneling microscope, an instrument for imaging surfaces at the atomic level. The first successful scanning tunneling microscope experiment was done by Gerd Binnig and Heinrich Rohrer. The key to their success was using a feedback loop to regulate gap distance between the sample and the probe.
Scanning tunneling spectroscopy (STS), an extension of scanning tunneling microscopy (STM), is used to provide information about the density of electrons in a sample as a function of their energy.
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Counter-scanning (CS) is a scanning method that allows correcting raster distortions caused by drift of the probe of scanning microscope relative to the measured surface. During counter-scanning two surface scans, viz., direct scan and counter scan are obtained. The counter scan starts in the point where the direct scan ends. This point is called the coincidence point (CP). With the counter scan, the probe movement along the raster line and the probe movement from one raster line to the other raster line are carried out along the directions that are opposite to the movements in the direct scan. The obtained pair of images is called counter-scanned images (CSIs).
Nanometrology is a subfield of metrology, concerned with the science of measurement at the nanoscale level. Nanometrology has a crucial role in order to produce nanomaterials and devices with a high degree of accuracy and reliability in nanomanufacturing.
Highly oriented pyrolytic graphite (HOPG) is a highly pure and ordered form of synthetic graphite. It is characterised by a low mosaic spread angle, meaning that the individual graphite crystallites are well aligned with each other. The best HOPG samples have mosaic spreads of less than 1 degree.
Local oxidation nanolithography (LON) is a tip-based nanofabrication method. It is based on the spatial confinement on an oxidation reaction under the sharp tip of an atomic force microscope.
A recurrence tracking microscope (RTM) is a microscope that is based on the quantum recurrence phenomenon of an atomic wave packet. It is used to investigate the nano-structure on a surface.
Thermal scanning probe lithography (t-SPL) is a form of scanning probe lithography (SPL) whereby material is structured on the nanoscale using scanning probes, primarily through the application of thermal energy.
NanoWorld is the global market leader for tips for Scanning Probe Microscopy (SPM) and Atomic Force Microscopy (AFM). The Atomic Force Microscope (AFM) is the defining instrument for the whole field of nanoscience and nanotechnology. It enables its users in research and high-tech industry to investigate materials at the atomic scale. AFM probes are the key consumable, the “finger” that enables the scientist to scan surfaces point-by-point at the atomic scale. Consistent high quality of the scanning probes is vital for reproducible results.
Nanosensors is a brand of SPM and AFM probes for atomic force microscopy (AFM) and scanning probe microscopy (SPM).
Non-contact atomic force microscopy (nc-AFM), also known as dynamic force microscopy (DFM), is a mode of atomic force microscopy, which itself is a type of scanning probe microscopy. In nc-AFM a sharp probe is moved close to the surface under study, the probe is then raster scanned across the surface, the image is then constructed from the force interactions during the scan. The probe is connected to a resonator, usually a silicon cantilever or a quartz crystal resonator. During measurements the sensor is driven so that it oscillates. The force interactions are measured either by measuring the change in amplitude of the oscillation at a constant frequency just off resonance or by measuring the change in resonant frequency directly using a feedback circuit to always drive the sensor on resonance.
The operation of a photon scanning tunneling microscope (PSTM) is analogous to the operation of an electron scanning tunneling microscope (ESTM), with the primary distinction being that PSTM involves tunneling of photons instead of electrons from the sample surface to the probe tip. A beam of light is focused on a prism at an angle greater than the critical angle of the refractive medium in order to induce total internal reflection (TIR) within the prism. Although the beam of light is not propagated through the surface of the refractive prism under TIR, an evanescent field of light is still present at the surface.
A probe tip in scanning microscopy is a very sharp object made from metal or other materials, like a sewing needle with a point at one end with nano or sub-nanometer order of dimension. It can interact with up to one molecule or atom of a given surface of a sample that can reveal authentic properties of the surface such as morphology, topography, mapping and electrical properties of a single atom or molecule on the surface of the sample.
Multi-tip scanning tunneling microscopy extends scanning tunneling microscopy (STM) from imaging to dedicated electrical measurements at the nanoscale like a ″multimeter at the nanoscale″. In materials science, nanoscience, and nanotechnology, it is desirable to measure electrical properties at a particular position of the sample. For this purpose, multi-tip STMs in which several tips are operated independently have been developed. Apart from imaging the sample, the tips of a multi-tip STM are used to form contacts to the sample at desired locations and to perform local electrical measurements.
References
- ↑ R. V. Lapshin (2004). "Feature-oriented scanning methodology for probe microscopy and nanotechnology" (PDF). Nanotechnology. UK: IOP. 15 (9): 1135–1151. Bibcode:2004Nanot..15.1135L. doi:10.1088/0957-4484/15/9/006. ISSN 0957-4484.
- ↑ R. V. Lapshin (2011). "Feature-oriented scanning probe microscopy". In H. S. Nalwa (ed.). Encyclopedia of Nanoscience and Nanotechnology (PDF). 14. USA: American Scientific Publishers. pp. 105–115. ISBN 978-1-58883-163-7.
- ↑ R. Lapshin (2014). "Feature-oriented scanning probe microscopy: precision measurements, nanometrology, bottom-up nanotechnologies" (PDF). Electronics: Science, Technology, Business. Russian Federation: Technosphera Publishers (Special issue “50 years of the Institute of Physical Problems”): 94–106. ISSN 1992-4178. (in Russian).
- ↑ D. W. Pohl, R. Möller (1988). ""Tracking" tunneling microscopy". Review of Scientific Instruments. USA: AIP Publishing. 59 (6): 840–842. Bibcode:1988RScI...59..840P. doi:10.1063/1.1139790. ISSN 0034-6748.
- ↑ B. S. Swartzentruber (1996). "Direct measurement of surface diffusion using atom-tracking scanning tunneling microscopy". Physical Review Letters. USA: American Physical Society. 76 (3): 459–462. Bibcode:1996PhRvL..76..459S. doi:10.1103/PhysRevLett.76.459. ISSN 0031-9007. PMID 10061462.
