According to a report by the Physicist Network on June 4, researchers at the Center for Nanophysics and Advanced Materials at the University of Maryland have developed a new type of thermal electron bolometer that can be widely used in the field of biological and chemical weapons. Distance detection technology, airport security scanners and other areas of security imaging technology, and promote research on the structure of the universe. The related research report was published in the journal Nature·Nanotechnology published on June 3. Scientists have developed this bolometer using double-layer graphene. Graphene has a band gap with zero energy consumption, so it can absorb photons of any energy form, especially photons with very low energy, such as terahertz or infrared and submillimeter waves. The so-called photonic band gap means that a wave of a certain frequency range cannot propagate in this periodic structure, that is, the structure itself has a "forbidden band". The photonic band gap structure can make electromagnetic waves in certain bands completely unable to propagate therein, thus forming a band gap in the spectrum. Another characteristic of graphene is that it is well suited as a photon absorber: electrons that absorb energy can still maintain their own efficiency without losing energy due to the vibration of the material atoms. At the same time, this property also makes graphene have extremely low resistance. Researchers have designed a thermoelectron bolometer based on these two characteristics of graphene, which can work by measuring changes in resistance caused by the self-heating of electrons after absorption. In general, the electrical resistance of graphene is hardly affected by temperature and is not suitable for bolometers. So the researchers used a special technique: when the bilayer graphene is exposed to an electric field, it has a moderately sized band gap that both connects the resistance to temperature and maintains its ability to absorb low-energy infrared photons. . The researchers found that at 5 degrees Kelvin, the new bolometer can achieve the same sensitivity as existing bolometers, but at speeds that are more than 1,000 times faster. They speculate that they can surpass all current detection technologies at lower temperatures. The new device is particularly promising as a fast, sensitive, low-noise submillimeter wave detector. Submillimeter wave photons are emitted by relatively cool interstellar molecules and are therefore difficult to detect. By observing these interstellar molecular clouds, astronomers can study the early stages of star and galaxy formation. Sensitive sub-millimeter wave detectors can help build new observatories, determine the redshift and quality of very distant young galaxies, and advance research on dark energy and cosmic structure development. Although some challenges still exist, such as double-layer graphene can only absorb a small amount of incident light, which makes the new bolometer have higher resistance than similar equipment using other materials, so it is difficult to normal at high frequencies. Work, but the researchers said they are working hard to improve their design to overcome the above difficulties, and they also have great confidence in the bright prospects of graphene as a photoelectric detection material. (
3M Measuring Tape,Waterproof Tape Measure,Stainless Steel Tape Measure,Plastic Tape Measure
SHANGQIU CHAOYUE MEASURING TOOLS CO., LTD , https://www.equipmentool.com