Nanometer is a unit of length, which is about one hundred thousandth of a hair. Scientists strictly define it as:10-9 m nano has two meanings here:
The first is the concept of spatial scale. One nanometer is one thousandth of a micron, which is about one hundredth of the diameter of a person's hair, the arrangement period of several atoms and half of the diameter of DNA double-stranded molecules, indicating that it is a comprehensive science and technology to study atomic and molecular phenomena and the relationship between structure and function on the nanometer scale.
Another meaning is the concept of thinking mode, that is, human scientific research and production activities will develop to a smaller scale and a deeper level, such as from micron level to nanometer level; Production objects can be smaller and smaller, until nano-scale atomic and molecular devices.
Second, the meaning of nano-scale space
It is internationally recognized that 0. 1 ~ 100 nm is a nanoscale space. For the convenience of research, some people regard the size of 0. 1 ~ 1 micron as a sub-micron system, and the size of 1 ~ 100 nm divides the nano-system. The typical size < 1nm is a cluster. The material level involved in nano-scale space is a relatively independent intermediate field, which is neither macro nor micro, and is called mesoscopic research field.
Third, the significance of nanotechnology
Nanotechnology is a new frontier scientific research field that developed rapidly in the early 1990s.
Nanotechnology refers to the preparation, research and industrialization of nano-scale substances, as well as the comprehensive technical system of cross-research and industrialization of nano-scale substances.
The material level involved in nano-scale space is a relatively independent intermediate field that is neither macro nor micro, which is called mesoscopic research field.
Nano-science and technology is a high-tech subject that studies the motion law, characteristics and application of electrons, atoms and molecules in 1- 100 nanometer space. The ultimate goal of nanotechnology is to manipulate a single atom and molecule and build nanoscale devices or products with certain functions according to people's wishes. Obviously, nanotechnology is not equal to nano-material science, which includes nano-biology, nano-electronics, nano-mechanics, and of course nano-material science. This is a new field of interdisciplinary research.
Fourthly, the characteristics of nanotechnology.
1. They must have at least one dimension between 1 nm and 100 nm.
2. Their design process must reflect the ability of micro-manipulation, that is, they can fundamentally control the physical and chemical properties of molecular scale structures.
They can be combined to form a larger structure and have excellent electrical, chemical, mechanical and optical properties.
V. Traceability of nanotechnology:
1905 In the spring, Einstein wrote to his colleague Conrad Habicht, revealing that he would do four tasks this year, one of which was to measure the true size of molecules. In his doctoral thesis submitted on April 30th, he designed a new method to measure the molecular size, estimated that the diameter of a sugar molecule was about 1 nanometer, and connected the nanometer with the molecular size for the first time, which proved the existence of the molecule. This is one of the problems that attracted great attention in physics at the beginning of the 20th century.
In this doctoral thesis, Einstein designed a method to measure molecular size by Avogadro constant. When Einstein handed this paper to his tutor, Professor Alfred kleiner of the University of Zurich, the professor refused to accept it because it was too short. Einstein had to add some paragraphs before the paper was passed.
Einstein never thought that his doctoral thesis would be the source of nanotechnology developed a century later.
Memorabilia of the development of intransitive verbs in nanotechnology
1April 905 15: Einstein estimated that the diameter of a sugar molecule was about 1 nm in his doctoral thesis.
1959: American physicist Richard? Feynman predicted the rise of nanotechnology for the first time in his speech entitled "Great Development Potential at the Bottom".
1982: The scanning tunneling microscope came out.
1984: German physicist H? Professor Grant's team successfully developed nano-sized black metal powder, and nano-solid materials were born.
1986: Binig and basil invented the scanning tunneling microscope, and Luska shared the 1986 Nobel Prize in Physics.
1989: Igler, a scientist at almaden Research Center of IBM Company in the United States, successfully used scanning tunneling microscope to move the neon element on the surface of nickel crystal, rearrange a single element, and write the letters "IBM" with 35 xenon atoms arranged.
1990: "The First Symposium on Nanoscience and Technology" was held in the United States, which marked the formal birth of a new discipline-Nanoscience and Technology, which closely combined micro-basic theoretical research with contemporary high technology.
199l: Akio Inashima of Tsukuba Institute in Japan discovered carbon nanotubes, which are carbon tubes bent from graphite carbon atoms, with a diameter ranging from several nanometers to several tens of nanometers and a wall thickness of only a few nanometers.
1993: Beijing Vacuum Physics Laboratory of China Academy of Sciences manipulated atoms and successfully wrote the words "100" and "China".
1996: For the discovery of C60, Kruto, smalley and Cole won the Nobel Prize in chemistry.
June 5-438, 2000+10: The United States launched the National Nanometer Program (NNI).
August, 2000: Lucent Technology reported in the British magazine Nature that a kind of nanometer tweezers is made of DNA. Scientists at Cornell University in the United States have developed the world's first miniature medical equipment that can only be seen with a microscope-a nano "helicopter" that can enter human cells.
June 2006 5438+0: Berkeley University and Lawrence? Researchers at Bocelli National Laboratory have created the world's smallest laser-nano-lasers on nanowires.
July 3rd, 20001:"200 1 International Nano-materials High-level Forum and Technology Application Seminar" opened in Beijing International Conference Center, and nanotechnology attracted the attention of the central leadership.
20011:lucent technology made the world's smallest "nano-transistor" from a single organic molecule.
200 1 12.20: The American magazine Science published the top ten breakthroughs in the world in 20001year, among which nanotechnology has made many significant achievements, ranking among the best.
June 5438+ 10, 2002: Chinese and German scientists took the lead in freely manipulating a single biomacromolecule on the nanometer scale, and wrote "DNA" with DNA chains, which was published on the cover of the first issue of Nanocommunication magazine in the United States.
June 5-438, 2002+10/October 28: Shanghai held the "2002 Shanghai Nanotechnology Development Seminar", which outlined the future prospect of nanotechnology in Shanghai.
Seven, China scientists' research results.
Bai Chunli is one of the pioneers of scanning tunneling microscope in China and one of the influential and active scientists in the international STM field. Using this new technology, he has made outstanding contributions to the study of the surface structure of organic solids and macromolecules, and is the main promoter of the development of nanotechnology in China.
Xie, Institute of Physics, Chinese Academy of Sciences, took the lead in conducting research on carbon nanotubes in China and invented the method of directional growth of carbon nanotube arrays. The work on ultra-long carbon nanotubes was published in Nature magazine, and was reported by the Financial Times as the appearance of long carbon nanotubes, which created "the world's largest 3 mm", which was 1-2 orders of magnitude longer than the existing carbon nanotubes, and was rated as one of the top ten basic research progress in China 1998.
The superplastic ductility of nano-metal discovered by Luco Chinese Academy of Sciences is the first time that nano-copper is directly observed to extend more than 50 times at room temperature. This research was hailed as a major breakthrough in the field of metal materials and was rated as one of the top ten science and technology news in China in 2000.
The Institute of Solid State Physics, Chinese Academy of Sciences, Zhang Lide has developed advanced frontier technologies such as self-organized synthesis, template synthesis and mesoporous inner edge growth, and successfully synthesized nano-scale coaxial cables. The inner core is composed of carbide with a diameter of only 10nm, which can be used not only for the connection of high-density devices in the future, but also as parts of micromechanics and robots.
Hua, China, pioneers of nanoelectronics. In the field of molecular electronics and molecular computer, three kinds of single organic electromechanical bistable materials have been developed, which can be used to manufacture molecular logic switches. The transition time of these materials is extremely fast, and the conductance changes before and after the electric field can reach 654.38 0 million times. At the same time, there are other plates, memories and wires used to manufacture electronic equipment. The research of these new materials with a size of about 50 nanometers is in a leading position in the world.
Fan Shoushan and Tsinghua University successfully prepared one-dimensional GaN semiconductor nanorods with a diameter of 30 ~ 40 nanometers and a length of 25 microns by using the ammonia reaction of carbon nanotubes with oxidized crops for the first time in the world. This means that the space-limited reaction method of carbon nanotubes can be used to prepare one-dimensional nanostructures of more materials, and this research result is published in the journal Science. In 1998, it was rated as the top ten science and technology news.
Li Ming 'an, Shanghai Institute of Nuclear Research, China Academy of Sciences 1987, devoted to the research of scanning probe microscope (STM/AFM). At the beginning of 1989, the domestic scanning tunneling microscope (STM) was independently developed, and the application of STM in the study of DNA structure was carried out in cooperation with biologists, and the scanning probe microscopy of DNA and DNA- protein complex structure was conducted. Is one of the earliest promoters of nanotechnology in China.
Hu Jun Shanghai Jiaotong University and American scientists independently observed the double helix structure of DNA at 1989, which was rated as the top ten scientific and technological discoveries in the United States that year. During my visit to the United States, I invented the Scanning Dielectric Power Microscope (SPFM), studied the nanometer characteristics of water, and discovered the new natural phenomenon of "ice at room temperature" for the first time. Related work was published in Science and other magazines. At the same time, it has made international leading achievements in the study of nano-manipulation of biological macromolecules.
Eight, nano and nature
1 butterfly
★ Question:
Two physicists from the University of Exeter in the United Kingdom observed and analyzed the colors of the wings of a butterfly called Papilio with advanced optical instruments, and found that the wings of this butterfly were originally yellow and blue, but why do people look shiny green to the naked eye?
★ Answer:
It turns out that the wings of this big butterfly are covered with pits. The strangest thing is that these pits can only be measured in nanometers, and the bottom of these pits is yellow. Look carefully again: I found that these pits also formed a slope, but the slope was blue. When people observe with naked eyes, the light beam hits the pit bottom, and the light reflected from the pit bottom is yellow, while the light reflected from the pit slope is blue. Because the pit is too small, the reflected beams are mixed together and cannot be distinguished by human eyes, so it is regarded as green.
★ Application:
Some countries have applied this nanostructure to the anti-counterfeiting technology of coins and valuables.
2. Lotus leaf
★ Question:
The lotus, which is not stained with mud, is not wet regardless of wind and rain, and even every drop of water has aroused people's beautiful reverie. Why can lotus leaves be kept so clean?
★ Answer:
In the scanning electron microscope photos of lotus leaves, the surface structure is clearly visible, and those uneven nanostructures are the answers to be sought. There are many nano holes in this lotus leaf. When water droplets or oil droplets or even mixed liquids drop on this interface, a gas film will be formed, so that neither water nor oil can invade this surface, resulting in a wonderful phenomenon of hydrophobic and oleophobic.
★ Application:
This is a new fabric, which can permeate water vapor and prevent water droplets. At present, it has been used in military uniforms in hot and humid environment for a long time. In figure 1.3 (PTFE microporous membrane), hydrophobic nanoparticles are mixed in fabric fibers.