纳米科技全英文

1、The Era of Nanotechnology,Richard Phillips Feynman,Richard Phillips Feynman (May 11, 1918 February 15, 1988) was an American physicist known for his work in the path integral formulation of quantum mechanics, the theory of quantum electrodynamics and the physics of the superfluidity of supercooled l

2、iquid helium, as well as in particle physics (he proposed the parton model). For his contributions to the development of quantum electrodynamics, Feynman, jointly with Julian Schwinger , received the Nobel Prize in Physics in 1965,Richard Feynman,From the Stone Age, humans from the ground to the tip

3、 of the arrow all the chip lithography techniques, or with the integration of slashing the number of one-time Why can not we start from another angle, from single molecules or even atoms begin to be assembled to meet our requirements? He said: At least in my view, the laws of physics do not rule out

4、 creating things atom by atom potential,Richard Feynman,从石器时代开始，人类从磨尖箭头到光刻芯片的所有技术，都与一次性地削去或者融合数以亿计的原子以便把物质做成有用的形态有关。Feynman质问道，为什么我们不可以从另外一个角度出发，从单个的分子甚至原子开始进行组装，以达到我们的要求？,The question of Richard Feynman,The stone implements,The core plate,A brief introduction to the nanotechnology,Nanotechnology is

5、 the study of manipulating matter on an atomic and molecular scale. Generally, nanotechnology deals with structures sized between 1 to 100 nanometre in at least one dimension, and involves developing materials or devices within that size. Quantum mechenical effects are very important at this scale,

6、which is in the quantum realm. Nanotechnology is very diverse, ranging from extensions of conventional device physics to completely new approaches based upon molecular self-assembly, from developing new marerials with dimensions on the nanoscale to investigating whether we can directly control matte

7、r on th atomic scale.,Microscope,Microscope A microscope is an instrument used to see objects too small for the naked eye. The science of investigating small objects using such an instrument is called microscopy. Microscopic means invisible to the eye unless aided by a microscope. There are many typ

8、es of microscopes, the most common and first to be invented is the optical microscope which uses light to image the sample. Other major types of microscopes are the electron microscope (both the transmission electron microscope and the scanning electron microscope) and the various types of scanning

9、probe microscope.,electron microscope,TEM(Transmission Electron Microscopy) is a microscopy technique whereby a beam of electrons is transmitted through an ultra thin specimen, interacting with the specimen as it passes through. An image is formed from the interaction of the electrons transmitted th

10、rough the specimen; the image is magnified and focused onto an imaging device, such as a fluorescent screen, on a layer of photographic film, or to be detected by a sensor such as a CCD camera.,A Flea as imaged using an electron microscope,A dust mite dander,Quantum Mechanics,Quantum Mechanics Quant

11、um mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of the dual particle-like and wave-like behaviour and interaction of matter and energy. Quantum mechanics departs from classical mechanics primarily at the atomic and sub-atomic

12、 scales, the so-called quantum realm. In special cases some quantum mechanical processes are macroscopic, but these emerge only at extremely low or extremely high energies or temperatures.,Scanning electron microscope,SEM (SEM) scanning electron microscope is a type of microscope that images a sampl

13、e by scanning it with a high-energy beam of electrons in a raster scan pattern. The electrons interact with the atoms that make up the sample producing signals that contain information about the samples surface topography, composition, and other properties such as electrical conductivity. The types

14、of signals produced by an SEM include secondary electrons, back-scattered electrons (BSE), characteristic X-rays, light (cathodoluminescence),Scanning electron microscope,specimen current and transmitted electrons. Secondary electron detectors are common in all SEMs, but it is rare that a single mac

15、hine would have detectors for all possible signals. The signals result from interactions of the electron beam with atoms at or near the surface of the sample. In the most common or standard detection mode, secondary electron imaging or SEI, the SEM can produce very high-resolution images of a sample

16、 surface, revealing details about less than 1 to 5 nm in size. Due to the very narrow electron beam, SEM micrographs have a large depth of field yielding a characteristic three-dimensional appearance useful for understanding the surface structure of a sample. This is exemplified by the micrograph of

17、 pollen shown to the right. A wide range of magnifications is possible,STM,the birth of cluster science and the invention of the scanning tunneling microscope (STM). This development led to the discovery of fullerenes in 1985 and carbon nanotubes a few years later. In another development, the synthe

18、sis and properties of semiconductor nanocrystals was studied; this led to a fast increasing number of metal and metal oxide nanoparticles and quantum dots. The atomic force microscope was invented six years after the STM was invented. In 2000, the United States National Nanotechnology Initiative was

19、 founded to coordinate Federal nanotechnology research and development and is evaluated by the Presidents Council of Advisors on Science and Technology.,Procedure of STM,First, a voltage bias is applied and the tip is brought close to the sample by some coarse sample-to-tip control, which is turned

20、off when the tip and sample are sufficiently close. At close range, fine control of the tip in all three dimensions when near the sample is typically piezoelectric, maintaining tip-sample separation W typically in the 4-7 range, which is the equilibrium position between attractive (3W10) and repulsi

21、ve (W3) In this situation, the voltage bias will cause electrons to tunnel between the tip and sample, creating a current that can be measured. Once tunneling is established, the tips bias and position with respect to the sample can be varied (with the details of this variation depending on the expe

22、riment) and data is obtained from the resulting changes in current. If the tip is moved across the sample in the x-y plane, the changes in surface height and density of states cause changes in current. These changes are mapped in images. This change in current with respect to position can be measure

23、d itself, or the height, z, of the tip corresponding to a constant current can be measured. These two modes are called constant height mode and constant current mode, respectively. In constant current mode, feedback electronics adjust the height by a voltage to the piezoelectric height control mecha

24、nism. This leads to a height variation and thus the image comes from the tip topography across the sample and gives a constant charge density surface; this means contrast on the image is due to variations in charge density.,Current image of C60,Procedure of STM,In constant height mode, the voltage a

25、nd height are both held constant while the current changes to keep the voltage from changing; this leads to an image made of current changes over the surface, which can be related to charge density. The benefit to using a constant height mode is that it is faster, as the piezoelectric movements requ

26、ire more time to register the change in constant current mode than the voltage response in constant height mode. All images produced by STM are grayscale, with color optionally added in post-processing in order to visually emphasize important features. In addition to scanning across the sample, info

27、rmation on the electronic structure at a given location in the sample can be obtained by sweeping voltage and measuring current at a specific location. This type of measurement is called scanning tunneling spectroscopy (STS) and typically results in a plot of the local density of states as a functio

28、n of energy within the sample. The advantage of STM over other measurements of the density of states lies in its ability to make extremely local measurements: for example, the density of states at an impurity site can be compared to the density of states far from impurities.,Rain,chen xiang,nano mat

29、erial- Nanoparticles,nano material- Nanoparticles,Nanoparticles or nanocrystals made of metals, semiconductors, or oxides are of particular interest for their mechanical, electrical, magnetic, optical, chemical and other properties. Nanoparticles have been used as quantum dots and as chemical cataly

30、sts. Nanoparticles are of great scientific interest as they are effectively a bridge between bulk materials and atomic or molecular structures. A bulk material should have constant physical properties regardless of its size, but at the nano-scale this is often not the case. Size-dependent properties

31、 are observed such as quantum confinement in semiconductor particles, surface plasmon resonance in some metal particles and superparamagnetism in magnetic materials.,nano material-Sol-gel,Sol-gels and other ceramics are sometimes considered nanomaterials. The sol-gel process is a wet-chemical techni

32、que widely used recently in the fields of materials science and ceramic engineering. Such methods are used primarily for the fabrication of materials (typically a metal oxide) starting from a chemical solution (sol, short for solution) which acts as the precursor for an integrated network (or gel) o

33、f either discrete particles or network polymers.,Fullerenes,nano material- Fullerenes,The fullerenes are a class of allotropes of carbon which conceptually are graphene sheets rolled into tubes or spheres. These include the carbon nanotubes (or silicon nanotubes) which are of interest both because o

34、f their mechanical strength and also because of their electrical properties. For the past decade, the chemical and physical properties of fullerenes have been a hot topic in the field of research and development, and are likely to continue to be for a long time. In April 2003, fullerenes were under

35、study for potential medicinal use: binding specific antibiotics to the structure of resistant bacteria and even target certain types of cancer cells. The October 2005 issue of Chemistry and Biology contains an article describing the use of fullerenes as antimicrobial agents. In the field of nanotech

36、nology, heat resistance and superconductivity are among the properties attracting intense research. A common method used to produce fullerenes is to send a large current between two nearby graphite electrodes in an inert atmosphere. The resulting carbon plasma arc between the electrodes cools into s

37、ooty residue from which many fullerenes can be isolated.,guoshuyao,nano material- Fullerenes,Fullerenes -buckyballs,A fullerene is any molecule composed entirely of carbon, in the form of a hollow sphere, ellipsoid, or tube. Spherical fullerenes are also called buckyballs, and they resemble the ball

38、s used in Association Football. Cylindrical ones are called carbon nanotubes or buckytubes. Fullerenes are similar in structure to graphite, which is composed of stacked graphene sheets of linked hexagonal rings; but they may also contain pentagonal (or sometimes heptagonal) rings.,Fullerenes -bucky

39、balls,Many association footballs have the same shape as the Buckminsterfullerene C60,Fullerenes -buckyballs,The first fullerene to be discovered, and the familys namesake, buckminsterfullerene (C60), was prepared in 1985 by Richard Smalley, Robert Curl, James Heath, Sean OBrien, and Harold Kroto at

40、Rice University. The name was an homage to Buckminster Fuller, whose geodesic domes it resembles. The structure was also identified some five years earlier by Sumio Iijima, from an electron microscope image, where it formed the core of a bucky onion.Fullerenes have since been found to occur in natur

41、e. More recently, fullerenes have been detected in outer space. According to astronomer Letizia Stanghellini, Its possible that buckyballs from outer space provided seeds for life on Earth.” The discovery of fullerenes greatly expanded the number of known carbon allotropes, which until recently were

42、 limited to graphite, diamond, and amorphous carbon such as soot and charcoal. Buckyballs and buckytubes have been the subject of intense research, both for their unique chemistry and for their technological applications, especially in materials science, electronics, and nanotechnology.,CNTs,CNTs,Ca

43、rbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure. Nanotubes have been constructed with length-to-diameter ratio significantly larger than any other material. These cylindrical carbon molecules have novel properties, making them potentially useful in many applications i

44、n nanotechnology, electronics, optics, and other fields of materials science, as well as potential uses in architectural fields. They may also have applications in the construction of body armor. They exhibit extraordinary strength and unique electrical properties, and are efficient thermal conducto

45、rs. Nanotubes are members of the fullerene structural family, which also includes the spherical buckyballs. The ends of a nanotube may be capped with a hemisphere of the buckyball structure. Their name is derived from their size, since the diameter of a nanotube is on the order of a few nanometers),

46、 while they can be up to 18 centimeters in length Nanotubes are categorized as single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs). Applied quantum chemistry, specifically, orbital hybridization best describes chemical bonding in nanotubes. The chemical bonding of nanotubes is compose

47、d entirely of sp2 bonds, similar to those of graphite. These bonds, which are stronger than the sp3 bonds found in alkanes, provide nanotubules with their unique strength. Moreover, nanotubes naturally align themselves into ropes held together by van der Waals forces.,CNTs,CNTs,Most single-walled na

48、notubes (SWNT) have a diameter of close to 1 nanometer, with a tube length that can be many millions of times longer. The structure of a SWNT can be conceptualized by wrapping a one-atom-thick layer of graphite called graphene into a seamless cylinder. The way the graphene sheet is wrapped is repres

49、ented by a pair of indices (n,m) called the chiral vector. The integers n and m denote the number of unit vectors along two directions in the honeycomb crystal lattice of graphene. If m = 0, the nanotubes are called zigzag. If n = m, the nanotubes are called armchair. Otherwise, they are called chir

50、al. The diameter of a nanotube can be calculated from its (n,m) indices as follows d=a/3.141592653(nn+nm+mm)0.5 where a = 0.246 nm. Single-walled nanotubes are an important variety of carbon nanotube because they exhibit electric properties that are not shared by the multi-walled carbon nanotube (MW

51、NT) variants. In particular, their band gap can vary from zero to about 2 eV and their electrical conductivity can show metallic or semiconducting behavior, whereas MWNTs are zero-gap metals. Single-walled nanotubes are the most likely candidate for miniaturizing electronics beyond the micro electro

52、mechanical scale currently used in electronics. The most basic building block of these systems is the electric wire, and SWNTs can be excellent conductors.One useful application of SWNTs is in the development of the first intramolecular field effect transistors (FET). Production of the first intramo

53、lecular logic gate using SWNT FETs has recently become possible as well.4 To create a logic gate you must have both a p-FET and an n-FET. Because SWNTs are p-FETs when exposed to oxygen and n-FETs otherwise, it is possible to protect half of an SWNT from oxygen exposure, while exposing the other hal

54、f to oxygen. This results in a single SWNT that acts as a NOT logic gate with both p and n-type FETs within the same molecule. Single-walled nanotubes are dropping precipitously in price, from around $1500 per gram as of 2000 to retail prices of around $50 per gram of as-produced 4060% by weight SWN

55、Ts as of March 2010.,CNTs,Carbon nanotubes This rotating model of a carbon nanotube shows its 3D structure. Main article: Carbon nanotube Nanotubes are cylindrical fullerenes. These tubes of carbon are usually only a few nanometres wide, but they can range from less than a micrometer to several mill

56、imeters in length. They often have closed ends, but can be open-ended as well. There are also cases in which the tube reduces in diameter before closing off. Their unique molecular structure results in extraordinary macroscopic properties, including high tensile strength, high electrical conductivit

57、y, high ductility, high heat conductivity, and relative chemical inactivity (as it is cylindrical and planar that is, it has no exposed atoms that can be easily displaced). One proposed use of carbon nanotubes is in paper batteries, developed in 2007 by researchers at Rensselaer Polytechnic Institut

58、e. Another highly speculative proposed use in the field of space technologies is to produce high-tensile carbon cables required by a space elevator.,The advanced Nanotechnology of Japan,How nanobots are made,Nanotechnology as a whole is fairly simple to understand, but developing this universal tech

59、nology into a nanorobot has been slightly more complicated. To date, scientists have made significant progress but have not officially released a finished product in terms of a nanorobot that functions on an entirely mechanical basis. Many of the nanobot prototypes function quite well in certain respects but