The blackest material on Earth does not allow an aluminum disk to sink in water
This material is the same Vantablack 2 that cannot be measured with a spectrometer.
Two years ago, Surrey NanoSystems created the blackest material on Earth from nanotubes, called Vantablack (Vertically Aligned NanoTube Arrays). This material had the lowest reflection coefficient among all other known dark materials - only 0.036%. To demonstrate the properties of Vantablack, its creators shot a clip with a laser pointer. The spot of light that passes over the surface of this material simply disappears. It all looks like a black hole in miniature.
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Already this year, the specialists of the same company presented a new version of Vantablack, Vantablack 2 . Its reflection coefficient is not reported yet - simply because the sensitivity of modern spectrometers is too low. As a result, the reflection coefficient remains unknown - it is not equal to zero, it is impossible, but it tends to it.
Such material may be just a gift for the military - because it absorbs light, ultraviolet, infrared radiation. The military with the help of Vantablack 2 can create a "heat camouflage" to camouflage their equipment. It can also be used in science and technology — in particular, for calibrating optical equipment, preventing the scattering of light in telescopes, and improving IR cameras operating on Earth and in space. The material can also be used in thermal protection systems and as a coating for miniature assemblies and elements of various microelectromechanical devices. Probably, some accessories covered with such material will be popular among rich people. Material that does not reflect light - this can be the latest fashion! Interestingly, the scientists who created Vantablack are forbidden to talk to journalists about the potential military use of their material, and they also refused to voice the price for it, confining themselves to the phrase "he is very expensive." Previously, interest in the material expressed sculptor Anish Kapoor.
An example of a sculpture made using Vantablack. It looks very unusual
He also became the first representative of the world of art, which received the right to use such material. At the same time, Kapoor received an exclusive right to use Vantablack 2, which the sculptor’s colleagues are not too happy about. Now Vantablack is already used in art. In particular, even hoodies are going to cover this material. Although, judging by what its creators say about the price of Vantablack 2, such clothes will be not just expensive, but very expensive. Yes, and the conditions of its wearing are unclear. Won't it take away super-expensive coverage with ordinary rain, for example?
Vantablack 2 coating on aluminum
Interestingly, the developers do not provide detailed information on the process of creating Vantablack 2, it is only known that nanotubes grown at 430ºC in the Chemical Vapor Deposition chamber are used as the basis. The material is made up of millions of such nanotubes with a thickness of about 20 nanometers. This is 3500 times smaller than the diameter of a human hair - from 14 to 50 microns. According to expert estimates, 1 cm2 of the surface coated with Vantablack 2 contains about a billion nanotubes. The effect of absolute blackness is created due to the fact that the light falls between the tubes, is reflected between them and can not go outside. To understand the situation, scientists propose to imagine a situation where you walk through the forest, where the height of the trees is not 10-20 meters but 3 km and more. The lower tiers of such a forest will not see sunlight at all.
Now the developers have submitted a new video with the participation of their material. The video is unusual, since an aluminum disk floats on the surface of the water. Yes, we are accustomed to, that things are denser than water sink, but here everything is different. Surrey Nanosystems exhibit extreme hydrophobicity of Vantablack 2. The disc floats without problems on the surface of the water, and when it is removed, it remains completely dry. This property of the material is explained by the fact that it has an extremely low surface energy. In combination with a large disk surface, it helps him to float.
Here is the video itself:
It is also worth noting that if a person looks at Vantablack 2, he does not perceive an object with such a coating as something tangible. Instead, the brain tells us that it is a failure in blackness, nothing.
But still this is not an absolutely black body, as mentioned above, although the degree of absorption by the material of electromagnetic radiation of certain types and tends to 100%. An absolutely black body is a physical body, which at any temperature absorbs all the electromagnetic radiation falling on it in all ranges. Thus, for an absolutely black body, the absorptivity (the ratio of the absorbed energy to the energy of the incident radiation) is equal to 1 for emissions of all frequencies, directions of propagation and polarizations. Despite the name, an absolutely black body itself can emit electromagnetic radiation of any frequency and visually have a color. The emission spectrum of an absolutely black body is determined only by its temperature.
Two years ago, Surrey NanoSystems created the blackest material on Earth from nanotubes, called Vantablack (Vertically Aligned NanoTube Arrays). This material had the lowest reflection coefficient among all other known dark materials - only 0.036%. To demonstrate the properties of Vantablack, its creators shot a clip with a laser pointer. The spot of light that passes over the surface of this material simply disappears. It all looks like a black hole in miniature.
')
Already this year, the specialists of the same company presented a new version of Vantablack, Vantablack 2 . Its reflection coefficient is not reported yet - simply because the sensitivity of modern spectrometers is too low. As a result, the reflection coefficient remains unknown - it is not equal to zero, it is impossible, but it tends to it.
Such material may be just a gift for the military - because it absorbs light, ultraviolet, infrared radiation. The military with the help of Vantablack 2 can create a "heat camouflage" to camouflage their equipment. It can also be used in science and technology — in particular, for calibrating optical equipment, preventing the scattering of light in telescopes, and improving IR cameras operating on Earth and in space. The material can also be used in thermal protection systems and as a coating for miniature assemblies and elements of various microelectromechanical devices. Probably, some accessories covered with such material will be popular among rich people. Material that does not reflect light - this can be the latest fashion! Interestingly, the scientists who created Vantablack are forbidden to talk to journalists about the potential military use of their material, and they also refused to voice the price for it, confining themselves to the phrase "he is very expensive." Previously, interest in the material expressed sculptor Anish Kapoor.
An example of a sculpture made using Vantablack. It looks very unusual
He also became the first representative of the world of art, which received the right to use such material. At the same time, Kapoor received an exclusive right to use Vantablack 2, which the sculptor’s colleagues are not too happy about. Now Vantablack is already used in art. In particular, even hoodies are going to cover this material. Although, judging by what its creators say about the price of Vantablack 2, such clothes will be not just expensive, but very expensive. Yes, and the conditions of its wearing are unclear. Won't it take away super-expensive coverage with ordinary rain, for example?
Vantablack 2 coating on aluminum
Interestingly, the developers do not provide detailed information on the process of creating Vantablack 2, it is only known that nanotubes grown at 430ºC in the Chemical Vapor Deposition chamber are used as the basis. The material is made up of millions of such nanotubes with a thickness of about 20 nanometers. This is 3500 times smaller than the diameter of a human hair - from 14 to 50 microns. According to expert estimates, 1 cm2 of the surface coated with Vantablack 2 contains about a billion nanotubes. The effect of absolute blackness is created due to the fact that the light falls between the tubes, is reflected between them and can not go outside. To understand the situation, scientists propose to imagine a situation where you walk through the forest, where the height of the trees is not 10-20 meters but 3 km and more. The lower tiers of such a forest will not see sunlight at all.
Now the developers have submitted a new video with the participation of their material. The video is unusual, since an aluminum disk floats on the surface of the water. Yes, we are accustomed to, that things are denser than water sink, but here everything is different. Surrey Nanosystems exhibit extreme hydrophobicity of Vantablack 2. The disc floats without problems on the surface of the water, and when it is removed, it remains completely dry. This property of the material is explained by the fact that it has an extremely low surface energy. In combination with a large disk surface, it helps him to float.
Here is the video itself:
It is also worth noting that if a person looks at Vantablack 2, he does not perceive an object with such a coating as something tangible. Instead, the brain tells us that it is a failure in blackness, nothing.
But still this is not an absolutely black body, as mentioned above, although the degree of absorption by the material of electromagnetic radiation of certain types and tends to 100%. An absolutely black body is a physical body, which at any temperature absorbs all the electromagnetic radiation falling on it in all ranges. Thus, for an absolutely black body, the absorptivity (the ratio of the absorbed energy to the energy of the incident radiation) is equal to 1 for emissions of all frequencies, directions of propagation and polarizations. Despite the name, an absolutely black body itself can emit electromagnetic radiation of any frequency and visually have a color. The emission spectrum of an absolutely black body is determined only by its temperature.
Source: https://habr.com/ru/post/394997/
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