In the history of industrial engineering, technology characterized by length only occurred in microelectronics, but now we have nanotechnology. How small is one nanometer? The typical width of a human hair is 50 micrometers. One nanometer is 50,000th of a hair width.
Nanotechnology is the construction and use of functional structures designed from atomic or molecular scale with at least one characteristic dimension measured in nanometers. Their size allows them to exhibit novel and significantly improved physical, chemical, and biological properties, phenomena, and processes because of their size. When characteristic structural features are intermediate between isolated atoms and bulk materials in the range of about one to 100 nanometers, the objects often display physical attributes substantially different from those displayed by either atoms or bulk materials.
Phenomena at the nanometer scale are likely to be a completely new world. Properties of matter at nanoscale may not be as predictable as those observed at larger scales. Important changes in behavior are caused not only by continuous modification of characteristics with diminishing size, but also by the emergence of totally new phenomena such as quantum confinement, a typical example of which is that the color of light emitting from semiconductor nanoparticles depends on their sizes. Designed and controlled fabrication and integration of nanomaterials and nanodevices is likely to be revolutionary for science and technology.
Nanotechnology can provide unprecedented understanding about materials and devices and is likely to impact many fields. By using structure at nanoscale as a tunable physical variable, we can greatly expand the range of performance of existing chemicals and materials. Alignment of linear molecules in an ordered array on a substrate surface (self-assembled monolayers) can function as a new generation of chemical and biological sensors. Switching devices and functional units at nanoscale can improve computer storage and operation capacity by a factor of a million. Entirely new biological sensors facilitate early diagnostics and disease prevention of cancers. Nanostructured ceramics and metals have greatly improved mechanical properties, both in ductility and strength.
From the fundamental units of materials, all natural materials and systems establish their foundation at nanoscale; controlling matter at atomic or molecular levels means tailoring the fundamental properties, phenomena, and processes exactly at the scale where the basic properties are initiated. Nanotechnology could impact the production of virtually every human-made object – from automobiles and electronics to advanced diagnostics, surgery, advanced medicines, and tissue and bone replacements. To build electronic devices using atom-by-atom engineering, for example, we have to understand the interaction among atoms and molecules, how to manipulate them, how to keep them stable, how to communicate signals among them, and how to face them with the real world. This goal requires new knowledge, new tools, and new approaches.
To many people, nanotechnology may be understood as a process of ultra-miniaturization. Philosophically, changes in quantity result in changes in quality. Shrinkage in device size may lead to a change in operation principle due to quantum effect, which is the physics that governs the motion and interaction of electrons in atoms. In fact, the trend in product miniaturization will require new process measurement and control systems that can span across millimeter-, micrometer-, and nanometer-sized scales while accounting for the associated physics that govern the device and environment interaction at each specific size scale.
To consider the interactions among atoms in the nanometer scale, we need to introduce quantum mechanics and each atom has to be treated as a unit. To face the atoms with the real world in the millionmeter scale, we need to consider the collective properties of millions and millions of atoms, so that the matter is considered to be a continuous medium, and we use classical mechanics. The bridging of the two length scales requires new standardized architecture definitions that support multiple physics-based models and new computational representations that allow seamless transition and traversing through these various models.
Nanomanufacturing technologies that will support tailor-made products having functionally critical nanometer-scale dimensions are produced using massively parallel systems or self-assembly. The current research mainly focuses on nanoscience for discovering new materials, novel phenomena, new characterization tools, and fabricating nanodevices. The future impact of nanotechnology to human civilization is manufacturing. The small feature size in nanotechnology that limits application of wellestablished optical lithography and manipulation techniques causes industrial nanomanufacturing to remain a serious challenge to our technological advances.
Synthesis of nanomaterials is one of the most active fields in nanotechnology. There are numerous methods for synthesizing nanomaterials of various characteristics. An essential challenge in synthesis is controlling the structures at a high yield for industrial applications. Techniques are needed for atomic and molecular control of material building blocks, which can be assembled, used, and tailored for fabricating devices of multifunctionality in many applications.
Property characterization of nanomaterials is challenging because of the difficulties in manipulating structures of such small size. New tools and approaches must be developed to meet new challenges. Due to the high size and structure selectivity of nanomaterials, their physical properties could be quite diverse, depending on their atomic-scale structure, size, and chemistry. A typical example is the carbon nanotube, which is made of concentrical cylindrical graphite sheets with a diameter range from one to 400 nanometers and length of a few micrometers. Characterizing the mechanical properties of individual nanotubes, for example, is a challenge to many testing and measuring techniques because of the following constraints. First, the size (diameter and length) is rather small, prohibiting the application of wellestablished testing techniques. Tensile and creep testing require that the size of the sample be sufficiently large to be clamped rigidly by the sample holder without sliding. This is impossible for one-dimensional nanomaterials using conventional means. Second, the small size of the nanostructure makes their manipulation rather difficult, and specialized techniques are needed for picking up and installing individual nanostructures. Therefore, new methods and methodologies must be developed to quantify the properties of individual nanostructures.
Closed-loop process for teaching a laser to control quantum systems. The loop is entered with either an initial design estimate or even a random field in some cases. A current laser control field design is created with a pulse shaper and then applied to the sample. The action of the control is assessed, and the results are fed to a learning algorithm to suggest an improved field design for repeated excursions around the loop until the objective is satisfactorily achieved.
The essential mechanism of the QQC process is to generate localized and controlled high temperature and high pressure (under the three lasers) for both CVD (in/below the plasma) and PVD (on/inside the substrate). This is achieved through the resonance excitation between vibrational-rotational energy levels (under the CO2 laser) and the resonance ionization between band energy levels (under the excimer laser) with controlled cooling rate that is favorable for a higher sp3/sp2 ratio (under the Nd:YAG laser).
从本科课件上胡乱摘抄的。自己看看吧。反正这东西都是满大家都是的东西
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