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(SPIN elecTRONICS) Using the spin of an electron to represent binary data (0 or 1). Spintronics techniques are capable of much higher speed while requiring less power than the conventional method of using electron charges to represent data. (SPIN elecTRONICS) Using the spin of an electron to represent binary data (0 or 1). Spintronics techniques are capable of much higher speed while requiring less power than the conventional method of using electron charges to represent data.
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What has the author Henri-Jean M Drouhin written?
Henri-Jean M. Drouhin has written: 'Spintronics IV' -- subject(s): Semiconductors, Congresses, Spintronics
What is the design consideration of spintronics modulator?
Design considerations of a Spintronics modulator include its shape, overall size, and the intended application. Each modulator is designed to fit a specific application which requires considerable engineering.
Which memory uses the spin of electrons to store information?
A new experimental storage medium called "Spintronics"
What has the author E Y Tsymbal written?
E. Y. Tsymbal has written: 'Handbook of spin transport and magnetism' -- subject(s): Magnetism, Magnetoresistance, Spintronics
What will the next great event in computing be?
difficult to predict which will catch on but bets are on: carbon nanotubes, spintronics, quantum computing, DNA computing & optical computing are just a few.
What has the author M Razeghi written?
M. Razeghi has written: 'Antimony' -- subject(s): Antimony 'Long Wavelength Infrared Detectors (Optoelectronic Properties of Semiconductors An Superlattices, Vol 1)' 'Quantum sensing and nanophotonic devices VIII' -- subject(s): Optical properties, Congresses, Quantum electronics, Nanostructured materials, Quantum optics 'Carbon nanotubes, graphene, and associated devices II' -- subject(s): Carbon, Graphene, Congresses, Nanotubes, Nanostructured materials 'Spintronics III' -- subject(s): Semiconductors, Congresses, Spintronics 'Carbon nanotubes and associated devices' -- subject(s): Carbon, Congresses, Nanotubes, Nanostructured materials
What is spin injection?
Spin injection refers to the process of introducing a spin-polarized current or spin-polarized carriers (electrons or holes) into a material. This is often associated with spintronics, a field that explores the role of electron spin in addition to its fundamental electronic charge, aiming to develop new technologies for information processing and storage. Spin injection is crucial for manipulating and utilizing the spin properties of electrons in various devices such as spin transistors and spin valves.
Differentiate between volatile memory and non-volatile?
Non-volatile memory, nonvolatile memory, NVM or non-volatile storage, is computer memory that can retain the stored information even when not powered. Examples of non-volatile memory include read-only memory, flash memory, most types of magnetic computer storage devices (e.g. hard disks, floppy disk drives, and magnetic tape), optical disc drives, and early computer storage methods such as paper tape and punch cards.Non-volatile memory is typically used for the task of secondary storage, or long-term persistent storage. The most widely used form of primary storage today is a volatile form of random access memory (RAM), meaning that when the computer is shut down, anything contained in RAM is lost. Unfortunately, most forms of non-volatile memory have limitations that make them unsuitable for use as primary storage. Typically, non-volatile memory either costs more or performs worse than volatile random access memory.'''Volatile memory''', also known as '''volatile storage or primary storage device''', is [[computer memory]] that requires power to maintain the stored information, unlike [[non-volatile memory]] which does not require a maintained power supply.Most forms of modern [[random access memory]] are volatile storage, including [[dynamic random access memory]] and [[static random access memory]]. [[Content addressable memory]] and [[dual-ported RAM]] are usually implemented using volatile storage. Early volatile storage technologies include [[delay line memory]] and [[Williams tube]].RAM=Volatile memoryROM=NON-Volatile memory
Nanotechnology and its applications?
Nanotechnology advances affect all branches of engineering and science that deal directly with device components ranging in size between 1/10,000,000 (one ten http://www.answers.com/topic/millionth of a http://www.answers.com/topic/millimeter) and 1/10,0000 millimeter. At these scales, even the most sophisticated microtechnology-based instrumentation is useless. Engineers anticipate that advances in nanotechnology will allow the direct manipulation of molecules in biological samples (e.g., proteins or http://www.answers.com/topic/nucleic-acid) paving the way for the development of new materials that have a biological component or that can provide a biological interface. In addition to new tools, nanotechnology programs advance practical understanding of quantum physics. The internalization of quantum concepts is a necessary component of nanotechnology research programs because the laws of classical physics (e.g., classical mechanics or generalized gas laws) do not always apply to the atomic and near-atomic level. Nanotechnology and quantum physics. Quantum theory and mechanics describe the relationship between energy and matter on the atomic and http://www.answers.com/topic/subatomic scale. At the beginning of the twentieth century, German physicist Maxwell Planck (1858-1947) proposed that atoms absorb or http://www.answers.com/topic/emit electromagnetic radiation in bundles of energy termed quanta. This quantum concept seemed counter-intuitive to well-established Newtonian physics. Advancements associated with quantum mechanics (e.g., the uncertainty principle) also had profound implications with regard to the philosophical scientific arguments regarding the limitations of human knowledge. Planck's quantum theory, which also asserted that the energy of light (a http://www.answers.com/topic/photon) was directly proportional to its frequency, proved a powerful concept that accounted for a wide range of physical phenomena. Planck's constant relates the energy of a photon with the frequency of light. Along with the constant for the speed of light, Planck's constant (h = 6.626 x 10−34 Joule-second) is a fundamental constant of nature. Prior to Planck's work, electromagnetic radiation (light) was thought to travel in waves with an infinite number of available frequencies and wavelengths. Planck's work focused on attempting to explain the limited spectrum of light emitted by hot objects. Danish physicist Niels Bohr (1885-1962) studied Planck's quantum theory of radiation and worked in England with physicists J. J. Thomson (1856-1940), and Ernest Rutherford (1871-1937) to improve their classical models of the atom by incorporating quantum theory. During this time, Bohr developed his model of atomic structure. According to the Bohr model, when an electron is excited by energy it jumps from its ground state to an excited state (i.e., a higher energy orbital). The excited atom can then emit energy only in certain (quantized) amounts as its electrons jump back to lower energy orbits located closer to the nucleus. This excess energy is emitted in quanta of electromagnetic radiation (photons of light) that have exactly the same energy as the difference in energy between the orbits jumped by the electron. The electron quantum leaps between orbits proposed by the Bohr model accounted for Plank's observations that atoms emit or absorb electromagnetic radiation in quanta. Bohr's model also explained many important properties of the http://www.answers.com/topic/photoelectric-effect described by Albert Einstein (1879-1955). Einstein assumed that light was transmitted as a stream of particles termed photons. By extending the well-known wave properties of light to include a treatment of light as a stream of photons, Einstein was able to explain the photoelectric effect. Photoelectric properties are key to regulation of many microtechnology and proposed nanotechnology level systems. Quantum mechanics ultimately replaced electron "orbitals" of earlier atomic models with allowable values for angular momentum (angular velocity http://www.answers.com/topic/multiply by mass) and depicted electron positions in terms of probability "clouds" and regions. In the 1920s, the concept of http://www.answers.com/topic/quantization and its application to physical phenomena was further advanced by more mathematically complex models based on the work of the French physicist Louis Victor de Broglie (1892-1987) and Austrian physicist Erwin Schrödinger (1887-1961) that depicted the particle and wave nature of electrons. De Broglie showed that the electron was not merely a particle but a http://www.answers.com/topic/waveform. This proposal led Schrödinger to publish his wave equation in 1926. Schrödinger's work described electrons as a "standing wave" surrounding the nucleus, and his system of quantum mechanics is called wave mechanics. German physicist Max Born (1882-1970) and English physicist P. A. M. Dirac (1902-1984) made further advances in defining the http://www.answers.com/topic/subatomic-particle (principally the electron) as a wave rather than as a particle and in reconciling portions of quantum theory with relativity theory. Working at about the same time, German physicist Werner Heisenberg (1901-1976) formulated the first complete and self-consistent theory of quantum mechanics. Matrix mathematics was well established by the 1920s, and http://www.answers.com/topic/werner-heisenberg applied this powerful tool to quantum mechanics. In 1926, Heisenberg put forward his uncertainty principle which states that two http://www.answers.com/topic/complementary properties of a system, such as position and momentum, can never both be known exactly. This proposition helped cement the dual nature of particles (e.g., light can be described as having both wave and particle characteristics). Electromagnetic radiation (one region of the spectrum that comprises visible light) is now understood to have both particle and wave like properties. In 1925, Austrian-born physicist Wolfgang Pauli (1900-1958) published the Pauli exclusion principle states that no two electrons in an atom can simultaneously occupy the same quantum state (i.e., energy state). Pauli's specification of spin (+1/2 or −1/2) on an electron gave the two electrons in any http://www.answers.com/topic/suborbital differing quantum numbers (a system used to describe the quantum state) and made completely understandable the structure of the periodic table in terms of electron configurations (i.e., the energy-related arrangement of electrons in energy shells and suborbitals). In 1931, American chemist Linus Pauling published a paper that used quantum mechanics to explain how two electrons, from two different atoms, are shared to make a http://www.answers.com/topic/covalent-bond between the two atoms. Pauling's work provided the connection needed in order to fully apply the new quantum theory to chemical reactions. Advances in nanotechnology depend upon an understanding and application of these fundamental quantum principles. At the quantum level the smoothness of classical physics disappears and nanotechnologies are predicated on exploiting this quantum roughness. Applications The development of devices that are small, light, self-contained, use little energy and that will replace larger microelectronic equipment is one of the first goals of the anticipated nanotechnology revolution. The second phase will be marked by the introduction of materials not http://www.answers.com/topic/feasible at larger than nanotechnology levels. Given the nature of quantum http://www.answers.com/topic/variance, scientists http://www.answers.com/topic/theorize that single molecule sensors can be developed and that sophisticated memory storage and neural-like networks can be achieved with a very small number of molecules. Traditional engineering concepts undergo radical transformation at the atomic level. For example, nano-technology motors may drive gears, the cogs of which are composed of the atoms attached to a carbon ring. Nanomotors may themselves be driven by http://www.answers.com/topic/oscillate magnetic fields or high precision oscillating lasers. Perhaps the greatest promise for nanotechnology lies in potential http://www.answers.com/topic/biotechnology advances. Potential nano-level manipulation of DNA offers the opportunity to radically expand the horizons of genomic medicine and http://www.answers.com/topic/immunology. Tissue-based biosensors may unobtrusively be able to monitor and regulate site-specific medicine delivery or regulate physiological processes. Nanosystems might serve as highly sensitive detectors of toxic substances or used by inspectors to detect traces of biological or chemical weapons. In electronics and computer science, scientists assert that nanotechnologies will be the next major advance in computing and information processing science. Microelectronic devices rely on recognition and flips in electron gating (e.g. where differential states are ultimately represented by a series of binary numbers ["0" or "1"] that depict voltage states). In contrast, future quantum processing will utilize the identity of quantum states as set forth by quantum numbers. In quantum http://www.answers.com/topic/cryptography systems with the ability to http://www.answers.com/topic/decipherment encrypted information will rely on precise knowledge of manipulations used to achieve various atomic states. Nanoscale devices are constructed using a combination of fabrication steps. In the initial growth stage, layers of http://www.answers.com/topic/semiconductor materials are grown on a dimension limiting http://www.answers.com/topic/substrate. Layer composition can be altered to control electrical and/or optical characteristics. Techniques such as http://www.answers.com/topic/molecular-beam-epitaxy (http://www.answers.com/topic/mbe-abbreviation) and metallo-organic chemical vapor deposition (MOCVD) are capable of producing layers of a few atoms thickness. The developed pattern is then imposed on successive layers (the pattern transfer stage) to develop desired three dimensional structural characteristics. Nanotechnology Research In the United States, expenditures on nanotechnology development tops $500 million per year and is largely coordinated by the National Science Foundation and Department of Defense Advanced Research Projects Agency (DARPA) under the umbrella of the National Nano-technology Initiative. Other institutions with dedicated funding for nanotechnology include the Department of Energy (DOE) and National Institutes of Health (NIH). Research interests. Current research interests in nano-technology include programs to develop and exploit nanotubes for their ability to provide extremely strong bonds. Nanotubes can be http://www.answers.com/topic/flex and woven into fibers for use in ultrastrong-but also ultralight-bulletproof vests. Nanotubes are also excellent conductors that can be used to develop precise electronic http://www.answers.com/topic/circuitry. Other interests include the development of nanotechnology-based sensors that allow smarter autonomous weapons capable of a greater range of adaptations http://www.answers.com/topic/en-route to a target; materials that offer stealth characteristics across a broader span of the electromagnetic spectrum; self-repairing structures; and nanotechnology-based weapons to disrupt-but not destroy-electrical system infrastructure. Further Reading Books Mulhall, Douglas. Our Molecular Future: How Nanotechnology, Robotics, Genetics, and Artificial Intelligence Will Change Our World. Amherst, NY: Prometheus Books, 2002. Periodicals Bennewitz, R., et. al., "Atomic scale memory at a silicon surface." Nanotechnology 13 (2000): 499-502. Electronic National Science and Technology Council. "National Nano-technology Initiative." (March 19, 2003).http://www.answers.com/library/Wikipedia-cid-54347 nanotechnologyhttp://www.answers.com/topic/c60a-png-1 http://www.answers.com/topic/c60a-png-1Buckminsterfullerene C60, also known as the buckyball, is the simplest of the http://www.answers.com/topic/allotropes-of-carbon known as http://www.answers.com/topic/fullerene. Members of the fullerene family are a major subject of research falling under the nanotechnology umbrella.Nanotechnology refers broadly to a field of http://www.answers.com/topic/applied-science and technology whose unifying theme is the control of matter on the atomic and http://www.answers.com/topic/molecule scale, normally 1 to 100 nanometers, and the fabrication of devices within that size range. It is a highly http://www.answers.com/topic/interdisciplinarity field, drawing from fields such as http://www.answers.com/topic/applied-physics-1, http://www.answers.com/topic/materials-science, http://www.answers.com/topic/colloid science, http://www.answers.com/topic/semiconductor-device, http://www.answers.com/topic/supramolecular-chemistry, and even http://www.answers.com/topic/mechanical-engineering and http://www.answers.com/topic/electrical-engineering. Much speculation exists as to what new science and technology may result from these lines of research. Nanotechnology can be seen as an extension of existing sciences into the nanoscale, or as a recasting of existing sciences using a newer, more modern term. Two main approaches are used in nanotechnology. In the "bottom-up" approach, materials and devices are built from http://www.answers.com/topic/molecule components which http://www.answers.com/topic/self-assembly chemically by principles of http://www.answers.com/topic/molecular-recognition. In the "top-down" approach, nano-objects are constructed from larger entities without atomic-level control. The impetus for nanotechnology comes from a renewed interest in colloidal science, coupled with a new generation of analytical tools such as the http://www.answers.com/topic/atomic-force-microscope (AFM), and the http://www.answers.com/topic/scanning-tunneling-microscope (STM). Combined with refined processes such as http://www.answers.com/topic/electron-beam-lithography and http://www.answers.com/topic/molecular-beam-epitaxy-1, these instruments allow the deliberate manipulation of nanostructures, and led to the observation of novel phenomena. Examples of nanotechnology in modern use are the manufacture of polymers based on molecular structure, and the design of http://www.answers.com/topic/integrated-circuit layouts based on surface science. Despite the great promise of numerous nanotechnologies such as http://www.answers.com/topic/quantum-dot and http://www.answers.com/topic/carbon-nanotube, real commercial applications have mainly used the advantages of colloidal nanoparticles in bulk form, such as http://www.answers.com/topic/sunscreen, http://www.answers.com/topic/cosmetic, http://www.answers.com/topic/industrial-coating, and stain resistant clothing.Nanotechnologyc60a-png-1{| ! style="BACKGROUND: #e6e6e6; COLOR: #000000" | Topics | http://www.answers.com/topic/history-of-nanotechnology · http://www.answers.com/topic/implications-of-nanotechnologyhttp://www.answers.com/topic/list-of-nanotechnology-applications · http://www.answers.com/topic/list-of-nanotechnology-organizationshttp://www.answers.com/topic/nanotechnology-in-fiction · http://www.answers.com/topic/list-of-nanotechnology-topics ! style="BACKGROUND: #e6e6e6; COLOR: #000000; LINE-HEIGHT: 11pt" | Subfields and related fields | http://www.answers.com/topic/nanomedicinemolecular-self-assembly-1molecular-electronicsscanning-probe-microscopynanolithographyhttp://www.answers.com/topic/molecular-nanotechnology ! style="BACKGROUND: #e6e6e6; COLOR: #000000" | Nanomaterials | http://www.answers.com/topic/nanomaterials · http://www.answers.com/topic/fullerenecarbon-nanotubenanotube-membranefullerene-chemistryhttp://www.answers.com/topic/potential-applications-of-carbon-nanotubes · http://www.answers.com/topic/fullerenes-in-popular-culturehttp://www.answers.com/topic/timeline-of-carbon-nanotubes · http://www.answers.com/topic/allotropes-of-carbonhttp://www.answers.com/topic/nanoparticle · http://www.answers.com/topic/quantum-dothttp://www.answers.com/topic/colloidal-gold · http://www.answers.com/topic/colloidal-silver ! style="BACKGROUND: #e6e6e6; COLOR: #000000" | Molecular nanotechnology | http://www.answers.com/topic/molecular-assemblermechanosynthesishttp://www.answers.com/topic/nanorobotics · http://www.answers.com/topic/grey-gook-eric-drexlerengines-of-creation ----: Main article: http://www.answers.com/topic/history-of-nanotechnology The first use of the distinguishing concepts in 'nanotechnology' (but predating use of that name) was in "http://www.answers.com/topic/there-s-plenty-of-room-at-the-bottom," a talk given by physicist http://www.answers.com/topic/richard-feynman at an http://www.answers.com/topic/american-physical-society meeting at http://www.answers.com/topic/california-institute-of-technology on http://www.answers.com/topic/december-29, http://www.answers.com/topic/1959. Feynman described a process by which the ability to manipulate individual atoms and molecules might be developed, using one set of precise tools to build and operate another proportionally smaller set, so on down to the needed scale. In the course of this, he noted, scaling issues would arise from the changing magnitude of various physical phenomena: gravity would become less important, surface tension and http://www.answers.com/topic/van-der-waals-force-1 would become more important, etc. This basic idea appears feasible, and exponential assembly enhances it with http://www.answers.com/topic/angle-of-parallelism to produce a useful quantity of end products. The term "nanotechnology" was defined by http://www.answers.com/topic/tokyo-university-of-science Professor http://www.answers.com/topic/norio-taniguchi in a http://www.answers.com/topic/1974 paper (N. Taniguchi, "On the Basic Concept of 'Nano-Technology'," Proc. Intl. Conf. Prod. Eng. Tokyo, Part II, Japan Society of Precision Engineering, 1974.) as follows: "'Nano-technology' mainly consists of the processing of, separation, consolidation, and deformation of materials by one atom or by one molecule." In the 1980s the basic idea of this definition was explored in much more depth by http://www.answers.com/topic/k-eric-drexler, who promoted the technological significance of nano-scale phenomena and devices through speeches and the books http://www.answers.com/topic/engines-of-creation (1986) and Nanosystems: Molecular Machinery, Manufacturing, and Computation, (1998, ISBN 0-471-57518-6), and so the term acquired its current sense. Nanotechnology and nanoscience got started in the early 1980s with two major developments; the birth of http://www.answers.com/topic/cluster-physics science and the invention of the http://www.answers.com/topic/scanning-tunneling-microscope (STM). This development led to the discovery of http://www.answers.com/topic/fullerene in 1986 and http://www.answers.com/topic/carbon-nanotube a few years later. In another development, the synthesis and properties of semiconductor http://www.answers.com/topic/nanocrystal was studied. This led to a fast increasing number of metal oxide nanoparticles of http://www.answers.com/topic/quantum-dot. The http://www.answers.com/topic/atomic-force-microscope was invented five years after the STM was invented. The AFM uses atomic force to see the atoms. http://www.answers.com/main/Record2?a=NR&url=http%3A%2F%2Fcommons.wikimedia.org%2Fwiki%2FImage%3AWikibooks-logo-en.svgWikibooks' [[wikibooks:|]] has more about this subject: The Opensource Handbook of Nanoscience and NanotechnologyOne nanometer (nm) is one billionth, or 10-9 of a meter. For comparison, typical carbon-carbon http://www.answers.com/topic/bond-length, or the spacing between these atoms in a molecule, are in the range .12-.15 nm, and a http://www.answers.com/topic/dna double-helix has a diameter around 2 nm. On the other hand, the smallest http://www.answers.com/topic/cell lifeforms, the bacteria of the genus http://www.answers.com/topic/mycoplasma-2, are around 200 nm in length. To put that scale in to context the comparative size of a nanometer to a meter is the same as that of a marble to the size of the earthhttp://www.answers.com/topic/nanotechnology#wp-_note-NationalG. Or another way of putting it: a nanometer is the amount a man's beard grows in the time it takes him to raise the razor to his facehttp://www.answers.com/topic/nanotechnology#wp-_note-NationalG. Image:Atomic resolution Au100.JPG‎ Image of http://www.answers.com/topic/surface-reconstruction on a clean http://www.answers.com/topic/gold(http://www.answers.com/topic/miller-index) surface, as visualized using http://www.answers.com/topic/scanning-tunneling-microscope. The individual http://www.answers.com/topic/atom composing the surface are visible.: Main article: http://www.answers.com/topic/nanomaterials A number of physical phenomena become noticeably pronounced as the size of the system decreases. These include http://www.answers.com/topic/statistical-mechanics effects, as well as http://www.answers.com/topic/quantum-mechanics effects, for example the "http://www.answers.com/topic/quantum size effect" where the electronic properties of solids are altered with great reductions in particle size. This effect does not come into play by going from macro to micro dimensions. However, it becomes dominant when the nanometer size range is reached. Additionally, a number of http://www.answers.com/topic/physical-property-2 change when compared to macroscopic systems. One example is the increase in surface area to volume of materials. This catalytic activity also opens potential risks in their interaction with http://www.answers.com/topic/biomaterial. Materials reduced to the nanoscale can suddenly show very different properties compared to what they exhibit on a macroscale, enabling unique applications. For instance, opaque substances become transparent (copper); inert materials become catalysts (platinum); stable materials turn combustible (aluminum); solids turn into liquids at room temperature (gold); insulators become conductors (silicon). A material such as http://www.answers.com/topic/gold, which is chemically inert at normal scales, can serve as a potent chemical catalyst at nanoscales. Much of the fascination with nanotechnology stems from these unique quantum and surface phenomena that matter exhibits at the nanoscale.: Main article: http://www.answers.com/topic/molecular-self-assembly-1 Modern http://www.answers.com/topic/chemical-synthesis has reached the point where it is possible to prepare small http://www.answers.com/topic/molecule to almost any structure. These methods are used today to produce a wide variety of useful chemicals such as http://www.answers.com/topic/drug or commercial http://www.answers.com/topic/polymer. This ability raises the question of extending this kind of control to the next-larger level, seeking methods to assemble these single molecules into http://www.answers.com/topic/supramolecular-assembly consisting of many molecules arranged in a well defined manner. These approaches utilize the concepts of http://www.answers.com/topic/molecular-self-assembly-1 and/or http://www.answers.com/topic/supramolecular-chemistry to automatically arrange themselves into some useful conformation through a http://www.answers.com/topic/bottom-up-2 approach. The concept of http://www.answers.com/topic/molecular-recognition is especially important: molecules can be designed so that a specific conformation or arrangement is favored due to http://www.answers.com/topic/noncovalent-bonding http://www.answers.com/topic/intermolecular-force. The Watson-Crick http://www.answers.com/topic/base-pair rules are a direct result of this, as is the specificity of an http://www.answers.com/topic/enzyme being targeted to a single http://www.answers.com/topic/substrate-biochemistry, or the specific http://www.answers.com/topic/protein-folding itself. Thus, two or more components can be designed to be complementary and mutually attractive so that they make a more complex and useful whole. Such bottom-up approaches should, broadly speaking, be able to produce devices in parallel and much cheaper than top-down methods, but could potentially be overwhelmed as the size and complexity of the desired assembly increases. Most useful structures require complex and thermodynamically unlikely arrangements of atoms. Nevertheless, there are many examples of self-assembly based on molecular recognition in http://www.answers.com/topic/biology-3, most notably http://www.answers.com/topic/base-pair and http://www.answers.com/topic/enzyme-http://www.answers.com/topic/substrate-biochemistry interactions. The challenge for nanotechnology is whether these principles can be used to engineer novel constructs in addition to natural ones.: Main article: http://www.answers.com/topic/molecular-nanotechnology Molecular nanotechnology, sometimes called molecular manufacturing, is a term given to the concept of engineered nanosystems (nanoscale machines) operating on the molecular scale. It is especially associated with the concept of a http://www.answers.com/topic/molecular-assembler, a machine that can produce a desired structure or device atom-by-atom using the principles of http://www.answers.com/topic/mechanosynthesis. Manufacturing in the context of productive nanosystems is not related to, and should be clearly distinguished from, the conventional technologies used to manufacture nanomaterials such as carbon nanotubes and nanoparticles. When the term "nanotechnology" was independently coined and popularized by http://www.answers.com/topic/k-eric-drexler (who at the time was unaware of an http://www.answers.com/topic/history-of-nanotechnology by http://www.answers.com/topic/norio-taniguchi) it referred to a future manufacturing technology based on http://www.answers.com/topic/molecular-machine-1 systems. The premise was that molecular-scale biological analogies of traditional machine components demonstrated molecular machines were possible: by the countless examples found in biology, it is known that billions of years of evolutionary feedback can produce sophisticated, http://www.answers.com/topic/stochastic optimised biological machines. It is hoped that developments in nanotechnology will make possible their construction by some other means, perhaps using http://www.answers.com/topic/bionics principles. However, Drexler and other researchers have proposed that advanced nanotechnology, although perhaps initially implemented by biomimetic means, ultimately could be based on mechanical engineering principles, namely, a manufacturing technology based on the mechanical functionality of these components (such as gears, bearings, motors, and structural members) that would enable programmable, positional assembly to atomic specification (PNAS-1981). The physics and engineering performance of exemplar designs were analyzed in Drexler's book Nanosystems. But Drexler's analysis is very qualitative and does not address very pressing issues, such as the "fat fingers" and "Sticky fingers" problems. In general it is very difficult to assemble devices on the atomic scale, as all one has to position atoms are other atoms of comparable size and stickyness. Another view, put forth by Carlo Montemagno, is that future nanosystems will be hybrids of silicon technology and biological molecular machines. Yet another view, put forward by the late http://www.answers.com/topic/richard-smalley, is that mechanosynthesis is impossible due to the difficulties in mechanically manipulating individual molecules. This led to an exchange of letters in the http://www.answers.com/topic/american-chemical-society publication Chemical & Engineering News in 2003. Though biology clearly demonstrates that molecular machine systems are possible, non-biological molecular machines are today only in their infancy. Leaders in research on non-biological molecular machines are Dr. Alex Zettl and his colleagues at Lawrence Berkeley Laboratories and UC Berkeley. They have constructed at least three distinct molecular devices whose motion is controlled from the desktop with changing voltage: a nanotube http://www.answers.com/topic/nanomotor, a molecular actuator, and a nanoelectromechanical relaxation oscillator. An experiment indicating that positional molecular assembly is possible was performed by Ho and Lee at http://www.answers.com/topic/cornell-university in 1999. They used a scanning tunneling microscope to move an individual carbon monoxide molecule (CO) to an individual iron atom (Fe) sitting on a flat silver crystal, and chemically bound the CO to the Fe by applying a voltage. http://www.answers.com/topic/nanocartriangle-jpg-1 http://www.answers.com/topic/nanocartriangle-jpg-1Space-filling model of the http://www.answers.com/topic/nanocar on a surface, using http://www.answers.com/topic/fullerene as wheels.http://www.answers.com/topic/rotaxane-jpg-1 http://www.answers.com/topic/rotaxane-jpg-1Graphical representation of a http://www.answers.com/topic/rotaxane, useful as a molecular switch.http://www.answers.com/main/Record2?a=NR&url=http%3A%2F%2Fcommons.wikimedia.org%2Fwiki%2FImage%3AAchermann7RED.jpg http://www.answers.com/main/Record2?a=NR&url=http%3A%2F%2Fcommons.wikimedia.org%2Fwiki%2FImage%3AAchermann7RED.jpgThis device transfers energy from nano-thin layers of http://www.answers.com/topic/quantum-well to http://www.answers.com/topic/nanocrystal above them, causing the nanocrystals to emit visible light. [1]As nanotechnology is a very broad term, there are many disparate but sometimes overlapping subfields that could fall under its umbrella. The following avenues of research could be considered subfields of nanotechnology. This includes subfields which develop or study materials having unique properties arising from their nanoscale dimensions. * http://www.answers.com/topic/colloid science has given rise to many materials which may be useful in nanotechnology, such as http://www.answers.com/topic/carbon-nanotube and other http://www.answers.com/topic/fullerene, and various http://www.answers.com/topic/nanoparticle and http://www.answers.com/topic/nanorod. * http://www.answers.com/topic/nanomaterials can also be used for bulk applications; most present commercial applications of nanotechnology are of this flavor. * Progress has been made in using these materials for medical applications; see nanomedicine. These seek to arrange smaller components into more complex assemblies. * DNA Nanotechnology utilises the specificity of http://www.answers.com/topic/base-pair to construct well-defined structures out of http://www.answers.com/topic/dna and other http://www.answers.com/topic/nucleic-acid. * More generally, molecular-self-assembly-1 seeks to use concepts of http://www.answers.com/topic/supramolecular-chemistry, and http://www.answers.com/topic/molecular-recognition in particular, to cause single-molecule components to automatically arrange themselves into some useful conformation. These seek to create smaller devices by using larger ones to direct their assembly. * Many technologies descended from conventional semiconductor-device-fabricationfor fabricating http://www.answers.com/topic/microprocessor are now capable of creating features smaller than 100 nm, falling under the definition of nanotechnology. http://www.answers.com/topic/giant-magnetoresistance-1-based hard drives already on the market fit this description,http://www.answers.com/topic/nanotechnology#wp-_note-0 as do http://www.answers.com/topic/atomic-layer-deposition (ALD) techniques. http://www.answers.com/topic/peter-gr-nberg and http://www.answers.com/topic/albert-fert received http://www.answers.com/topic/nobel-prize-in-physics for their discovery of Giant magnetoresistance and contributions to the field of spintronics in 2007.http://www.answers.com/topic/nanotechnology#wp-_note-1 * Solid-state techniques can also be used to create devices known as nanoelectromechanical-systemsor NEMS, which are related to http://www.answers.com/topic/microelectromechanical-systems or MEMS. * http://www.answers.com/topic/atomic-force-microscope tips can be used as a nanoscale "write head" to deposit a chemical on a surface in a desired pattern in a process called dip-pen-nanolithography. This fits into the larger subfield of http://www.answers.com/topic/nanolithography. These seek to develop components of a desired functionality without regard to how they might be assembled. * molecular-electronics seeks to develop molecules with useful electronic properties. These could then be used as single-molecule components in a nanoelectronic device. For an example see http://www.answers.com/topic/rotaxane. * Synthetic chemical methods can also be used to create synthetic-molecular-motors, such as in a so-called http://www.answers.com/topic/nanocar. |}
