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-This dot is 100,000 nanometers
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--------- #1457 - Quantum Dots, a 10 nanometer window-
- Quantum Dots are small pieces of semiconductor material, very small pieces, only 10 nanometers in diameter. Being so small brings unique properties following the rules of Quantum Mechanics.
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- The smaller the size of the crystal the larger the band gap. The band gap is the difference in energy level between the valence band and the lowest conduction band. Energy of the right amount excites the dot to higher energy and the energy is released when the crystal returns to its resting state. Fluorescence results with the electron returns to the ground state and combines with a hole.
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- Some examples of how Quantum Dots are being used:
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------------------------- Capturing light energy for solar panels
------------------------- Emitting entangled photons from light emitting diodes, LEDs
------------------------- Activating neurons in a Petri Dish
------------------------- Tuning laser cavities for fast, high power fiber optics, and computer multiplexing
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- Activating neurons is accomplished by shining a light on the Quantum Dot which generates a small electric field which opens up an ion channel in a nearby neuron, activating it. This is so much less intrusive than using electrodes to do the same thing.
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- Studying Parkinson’s Disease may allow deep brain stimulation without opening the skull. The Quantum Dots could be put where they wanted them by tagging them to proteins that target specific neurons in the brain. UV light could release drugs just where they were needed
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- Solar cells are having a hard time getting to 20% efficiency in today’s technology. Using Quantum Dots could allow 60% efficiency in converting sunlight to electricity.
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- The problem with the Sun’s energy is that it covers a wide spectrum of frequencies, which is a wide spectrum of energy levels. When just the right energy hits an electron it puts it in motion to create an electric current. However higher energy photons will excite electrons to no purpose and they loose their energy as heat, infrared energy. Quantum Dots could be used to slow the cooling rate of these “hot electrons” to produce more current
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- Using crystals of lead selenide, a semiconductor, less than 100 nanometers in size could absorb light energy in certain bandgaps or range of energies. This technique can increase the lifetime of a hot electron by 1000 times. By using electron conductors of titanium dioxide they can extract the electrons from the lead selenide nano crystals thus creating additional electric current from the hot electrons that were not being used.
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- Once Quantum Dots are tagged to a specific protein they can be used to track the natural flow of the protein inside a living cell. Using laser light the brightly reflective nano crystals can be tracked under a microscope. This technique of optical encoding is many times better than using conventional dyes and fluorescent labels.
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- Scientists hope to watch new drug compounds as they travel inside a cell. They could be injected into cancer cells to study growth under various conditions or therapies.
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- Quantum Dots that are just crystals 10 nanometers in diameter are opening up windows as wide as can be in the study of physics, chemistry, biology, computers, diode lasers, transistors, and quantum computing.
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- When you have entangled Quantum Dots you have Qubits that can secure messaging because any attempt at eavesdropping would alter the message in a detectable way. Quantum memory could solve mathematical problems so hard that a standard supercomputer couldn’t find the answer in the lifetime of the universe. Prime numbers for example used in electronic financial transactions become useless if the thief has a quantum computer.
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- Quantum Dots are valued for displays because they emit light in a very specific Gaussian distribution. They consume very little power. They can even produce “ White LEDs”
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- Quantum Dot photo detectors can be used in surveillance, machine vision, industrial inspection , spectroscopy, fluorescent biomedical imaging, ……. do you see how wide this window opens through a 10 nanometer dot. An announcement will be made shortly, stay tuned.
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707-536-3272, Tuesday, April 10, 2012
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