The transmission electron microscope is one that utilizes a high-energy electron beam that probes sample materials with a thickness less than 100 nanometers (nm). While some electrons are either absorbed or bounced of the material, others pass through it creating a magnified image as the one shown in the example. Current TEMs use digital cameras placed behind the material to capture and record images, magnifying images up to 30 million times. The TEM is the most popular microscope used the make images published in scientific journals on nanocrystals found in semiconductors.
The atomic force microscope (AFM) uses a small silicon tip as a probe to make images of sample material. While the probe move along the surface of the sample, the electrons of the atoms in the material begin to repel the electrons of the probe. The AFM then adjusts the height of the probe to keep the force of the sample constant. A mechanism records the movement of the probe and sends this information to a computer that will generate a three-dimensional image as shown in the slide. The image will show the exact topography of the surface.
A scanning tunneling microscope (STM) uses a wavelike property of electrons known as tunneling , which allows electrons emitted from a probe to penetrate, or tunnel into, the surface of the examined object. The electrons generate a tiny electric current that the STM measures. Similar to the atomic force microscope, the height of the probe in the STM is adjusted constantly to keep the current constant. In doing, so a detailed map of the material’ surface is produced as the example in this slide shows.
New solar cells are based on nanoparticles of semi conductors, nanofilms and nanotubes by embedding in a charge transfer medium. Films formed by sintering of nanometric particles of TiO2 (diameter 10-20 nm) combine high surface area, transparency, excellent stability and good electrical conductivity and are ideal for photovoltaic applications. Non porous oxide films are highly promising material for photovoltaic applications.
IMPACT OF NANOTECHNOLOGY IN OUR WORLD By:- SANCHIT SHARMA (07IT046)
The amount of space available to us for information storage (or other uses) is enormous. As first described in a lecture titled, 'There's Plenty of Room at the Bottom' in 1959 by Richard P. Feynman, there is nothing besides our clumsy size that keeps us from using this space. In his time, it was not possible for us to manipulate single atoms or molecules because they were far too small for our tools.
He described how the laws of physics do not limit our ability to manipulate single atoms and molecules. Feynman explored the possibility of manipulating the materials at a scale of individual atoms and molecules, imagining the whole of the encyclopedia Britannica written on the head of the pin.
Prof. Feynman described such atomic scale fabrication as a bottom-up approach, as opposed to the top-down approach that we are accustomed to.
Top-down Manufacturing :- It involves the construction of parts through methods such as cutting, carving and molding. Using these methods, we have been able to fabricate a remarkable variety of machinery and electronics devices.
Bottom-up manufacturing :- On the other hand, would provide components made of single molecules, which are held together by covalent forces that are far stronger than the forces that hold together macro-scale components. Further more, the amount of information that could be stored in devices build from the bottom up would be enormous
Nanotechnology is engineering at the molecular (groups of atoms) level. It is the collective term for a range of technologies, techniques and processes that involve the manipulation of matter at the smallest scale (from 1 to 100 nm 2 ).
The goal of nanotechnology is to control individual atoms and molecules to create computer chips and other devices that are thousands of times smaller than current technologies permit.
Nanotechnology is the technology of preference to make things small, light and cheap, nanotechnology based manufacturing is a method conceived for processing and rearranging of atoms to fabricate custom products
What is Nanoscale 12,756 Km 22 cm 0.7 nm Fullerenes C60 10 millions times smaller 1 billion times smaller
Very high sensitivity, low power sensor for detecting the chem/bio/nuclear threats.
Light weight military platforms, without sacrificing functionality, safety and soldier security
-Reduce fuel needs and logistical requirements
Reduce carry-on weight of soldier gear
-Increased functionality per unit weight
Examples of exciting applications of nanotechnology
Nanopowders — the unusual properties of particles less than 100 nm allow a range of new and improved materials with a breadth of applications, such as plastics that behave like ceramics or metals; new catalysts for environmental remediation; improved food shelf-life and packaging; and novel drug delivery devices .
The scale of nanopowders Porous metallic ‘nanocubes’ store large amounts of H2
Carbon nanotubes — Carbon nanotubes were demonstrated in 1991.
In this graphite can be rolled into a cylinder with a diameter of about 1 nm. These strong but light ‘carbon nanotubes’ are being developed for a raft of uses, such as sensors, fuel cells, computers and televisions.
a quantum computer will store information as quantum bits which can hold more than two values.
Quantum computers will also be able to utilize one other important characteristic of quantum particles known as entanglement. The property of entanglement makes it possible to assign and determine the value or the spin of a quantum particle by introducing an outside force.
Hewlett-Packard believes that silicon computer chips will probably reach a technical dead end in about a decade, to be replaced by tiny nanodevices described as ‘cross bar latches’.
The new device consists of a wire that is crossed by two other wires. The resulting junctions serve as switches that are only a few atoms across and can be programmed by a repeatable set of electrical pulses.
Nanotechnology opens the opportunity to produce cheaper and friendlier solar cells. Nanoparticles are perfect to absorb solar energy and they can be used in very thin layers on conventional metals to absorb incident solar energy.
nanofibres offers the potential of using the woven reinforcement as body armor. The future soldier’s uniform would incorporate soft woven ultra strong fabric with capabilities to become rigid when protect him against pollution, poisoning and enemy hazards.
Nanobots will be the next generation of nanomachines. Advanced nanobots will be able to sense and adapt to environmental stimuli such as heat, light, sounds, surface textures, and chemicals; perform complex calculations; move, communicate, and work together; repair or even replicate themselves