Ultraviolet radiation: application, action and protection from it

The energy of the Sun is electromagnetic waves, which are divided into several parts of the spectrum:

• X-rays - with the shortest wavelength (below 2 nm);
• the wavelength of ultraviolet radiation is from 2 to 400 nm;
• the visible part of the world that is captured by the eye of humans and animals (400-750 nm);
• warm oxidative (infrared) radiation (over 750 nm).

Each part finds its application and is of great importance in the life of the planet and all its biomass. We will consider what rays are in the range from 2 to 400 nm, where they are used and what role they play in people's lives.

UV discovery history

The first references date back to the 13th century in the descriptions of a philosopher from India. He wrote about the invisible violet light he had discovered. However, the technical capabilities of that time were clearly lacking in order to confirm this experimentally and study in detail.

It succeeded five centuries later, physicist from Germany Ritter. It was he who conducted experiments on silver chloride by its decay under the influence of electromagnetic radiation. The scientist saw that faster this process is not in the area of ​​light that was already open by that time and was called infrared, but in the opposite. It turned out that this is a new area, still not explored.

Thus, in 1842, ultraviolet radiation was discovered, the properties and application of which were subsequently subjected to careful analysis and study by various scientists. A great contribution to this was made by such people as: Alexander Beckerel, Warsaw, Danzig, Macedonio Melloni, Frank, Parfyonov, Galanin and others.

general characteristics

What is ultraviolet radiation, the use of which is today so widespread in various fields of human activity? Firstly, it should be noted that this kind of light spectrum appears only at very high temperatures from 1500 to 2000 ⁰ . It is in this interval that the UV reaches a peak in activity by exposure.

By its physical nature, this is an electromagnetic wave, the length of which varies widely - from 10 (sometimes from 2) to 400 nm. The entire range of this radiation is conventionally divided into two areas:

1. Near range. It reaches the Earth through the atmosphere and the ozone layer from the Sun. The wavelength is 380-200 nm.
2. Far (vacuum). It is actively absorbed by ozone, atmospheric oxygen, and atmospheric components. It is possible to investigate only with special vacuum devices, for which it got its name. The wavelength is 200-2 nm.

There is a classification of species that has ultraviolet radiation. Properties and application finds each of them.

1. Near.
2. Further.
3. Extreme.
4. Average.
5. Vacuum.
6. Longwave Black Light (UV-A).
7. Shortwave germicidal (UV-C).
8. Medium wave UV-B.

The wavelength of ultraviolet radiation for each species has its own, but all of them are within the common limits already indicated earlier.

UV-A, or so-called black light, is interesting. The fact is that this spectrum has a wavelength of 400-315 nm. It is on the border with visible light, which the human eye is capable of capturing. Therefore, such radiation, passing through certain objects or tissues, is able to pass into the region of visible violet light, and people distinguish it as a black, dark blue or dark purple hue.

Spectra that give sources of ultraviolet radiation can be of three types:

• ruler;
• continuous
• molecular (band).

The former are characteristic of atoms, ions, gases. The second group is for recombination, bremsstrahlung. Sources of the third type are most often found in the study of rarefied molecular gases.

UV sources

The main sources of UV rays fall into three broad categories:

• natural or natural;
• artificial, man-made;
• laser.

The first group includes the only type of concentrator and emitter - the Sun. It is the heavenly luminary that gives the most powerful charge of this type of waves, which are able to pass through the ozone layer and reach the Earth's surface. However, not with all its mass. Scientists put forward the theory that life on Earth began only when the ozone screen began to protect it from excessive penetration of harmful UV radiation at high concentrations.

It was during this period that protein molecules, nucleic acids and ATP began to exist. To this day, the ozone layer interacts closely with the bulk of UV-A, UV-B and UV-C, rendering them harmless and preventing them from passing through themselves. Therefore, protection from the ultraviolet radiation of the entire planet is solely his merit.

What determines the concentration of ultraviolet radiation penetrating the Earth? There are several key factors:

• ozone holes;
• height above sea level;
• solstice height;
• atmospheric dispersion;
• the degree of reflection of rays from earth's natural surfaces;
• state of cloud vapors.

The range of ultraviolet radiation penetrating the Earth from the Sun ranges from 200 to 400 nm.

The following sources are artificial. These include all those devices, devices, technical means that were designed by man to obtain the desired spectrum of light with the given parameters of the wavelength. This was done with the aim of obtaining ultraviolet radiation, the use of which can be extremely useful in various fields of activity. Artificial sources include:

1. Erythemic lamps with the ability to enhance the synthesis of vitamin D in the skin. This protects against rickets and treats it.
2. Devices for tanning salons, in which people receive not only a beautiful natural tan, but also are treated for diseases that arise when there is a lack of open sunlight (the so-called winter depression).
3. Attracting lamps that allow you to fight insects in indoor conditions is safe for humans.
4. Mercury-quartz devices.
5. Exilamp.
6. Luminescent devices.
7. Xenon lamps.
8. Gas discharge devices.
9. High temperature plasma.
10. Synchrotron radiation in accelerators.

Another type of source is lasers. Their work is based on the generation of various gases - both inert and not. Sources may include:

• nitrogen;
• argon;
• neon;
• xenon;
• organic scintillators;
• crystals.

More recently, about 4 years ago, a free electron laser was invented. The length of the ultraviolet radiation in it is equal to that observed under vacuum. UV laser suppliers are used in biotechnological, microbiological research, mass spectrometry and so on.

Biological effects on organisms

The effect of ultraviolet radiation on living things is twofold. On the one hand, with its lack, diseases can occur. This became clear only at the beginning of the last century. Artificial irradiation with special UV-A in the required standards is capable of:

• activate the immune system;
• cause the formation of important vasodilator compounds (histamine, for example);
• strengthen the musculoskeletal system;
• improve lung function, increase gas exchange rate;
• affect the speed and quality of metabolism;
• increase the tone of the body by activating the production of hormones;
• increase the permeability of the walls of blood vessels on the skin.

If UV-A enters the human body in sufficient quantities, then it does not have diseases such as winter depression or light starvation, and the risk of developing rickets is also significantly reduced.

The effect of ultraviolet radiation on the body is of the following types:

• bactericidal;
• anti-inflammatory;
• regenerative;
• painkiller.

These properties largely explain the widespread use of UV in medical institutions of any type.

However, in addition to the above advantages, there are also negative sides. There are a number of diseases and ailments that can be acquired if you do not receive or, on the contrary, take in excess the waves in question.

1. Skin cancer. This is the most dangerous exposure to ultraviolet radiation. Melanoma is able to form with the excessive influence of waves from any source - both natural and human-made. This is especially true for tanning enthusiasts. In all measure and caution are needed.
2. The destructive effect on the retina of the eyeballs. In other words, cataracts, pterygium, or a burn of the membrane may develop. The harmful excess UV exposure on the eyes has been proven by scientists for a long time and confirmed by experimental data. Therefore, when working with such sources, the safety rules must be observed . On the street you can protect yourself with the help of dark glasses. However, in this case, one should be wary of fakes, because if the glasses are not equipped with UV-repellent filters, then the destructive effect will be even stronger.
3. Burns on the skin. In the summer, they can be earned if you uncontrollably expose yourself to UV for a long time. In winter, you can get them because of the peculiarity of the snow to reflect almost completely these waves. Therefore, irradiation occurs both from the side of the Sun and from the side of snow.
4. Aging. If people are exposed to UV for a long time, then they begin to manifest very early signs of skin aging: lethargy, wrinkles, sagging. This is due to the fact that the protective barrier functions of the integuments are weakened and impaired.
5. Impact with consequences over time. They are manifested in the manifestations of negative influences not at a young age, but closer to old age.

All these results are consequences of violation of UV dosages, i.e. they arise when the use of ultraviolet radiation is carried out irrationally, improperly, and without observing safety measures.

Ultraviolet radiation: application

The main areas of use are based on the properties of the substance. This is also true for spectral wave radiation. So, the main characteristics of UV, on which its application is based, are:

• high level chemical activity;
• bactericidal effects on organisms;
• the ability to cause a glow of various substances in different shades visible to the human eye (luminescence).

This allows the widespread use of ultraviolet radiation. Application is possible in:

• spectrometric analyzes;
• astronomical research;
• medicine;
• sterilization;
• disinfection of drinking water;
• photolithography;
• analytical study of minerals;
• UV filters;
• for catching insects;
• to get rid of bacteria and viruses.

Each of these areas uses a specific type of UV with its own spectrum and wavelength. Recently, this type of radiation has been actively used in physical and chemical studies (establishing the electronic configuration of atoms, the crystal structure of molecules and various compounds, working with ions, analysis of physical transformations at various space objects).

There is another feature of the effects of UV on substances. Some polymeric materials can decompose under the influence of an intense constant source of these waves. For example, such as:

• polyethylene of any pressure;
• polypropylene;
• polymethyl methacrylate or organic glass.

What is the effect? Products from the above materials lose their color, crack, fade and, ultimately, collapse. Therefore, they are usually called sensitive polymers. This feature of the degradation of the carbon chain under conditions of sunlight is actively used in nanotechnology, X-ray lithography, transplantology and other fields. This is done mainly to smooth the surface roughness of the product.

Spectrometry is the main area of ​​analytical chemistry that specializes in identifying compounds and their composition by their ability to absorb UV light of a specific wavelength. It turns out that the spectra are unique for each substance; therefore, they can be classified according to the results of spectrometry.

Also, the use of ultraviolet bactericidal radiation is carried out to attract and destroy insects. The action is based on the ability of the insect eye to capture short-wavelength spectra invisible to humans. Therefore, animals fly to the source, where they are destroyed.

Use in tanning salons - special installations of vertical and horizontal type, in which the human body is exposed to UV-A. This is done to enhance the production of melanin in the skin, which gives it a darker color, smoothness. In addition, inflammation is dried and harmful bacteria on the surface of the integument are destroyed. Particular attention should be paid to eye protection, sensitive areas.

Medical field

The use of ultraviolet radiation in medicine is also based on its ability to destroy living organisms invisible to the eye - bacteria and viruses, and on the features that occur in the body during competent lighting with artificial or natural radiation.

The main indications for UV treatment can be identified in several paragraphs:

1. All types of inflammatory processes, open wounds, suppurations and open sutures.
2. With injuries of tissues, bones.
3. With burns, frostbite and skin diseases.
4. With respiratory ailments, tuberculosis, bronchial asthma.
5. With the occurrence and development of various types of infectious diseases.
6. With ailments accompanied by severe pain, neuralgia.
7. Diseases of the throat and nasal cavity.
8. Rickets and trophic gastric ulcer.
9. Dental diseases.
10. Regulation of blood pressure, normalization of the heart.
11. The development of cancerous tumors.
12. Atherosclerosis, renal failure and some other conditions.

All these diseases can have very serious consequences for the body. Therefore, treatment and prevention using UV is a real medical discovery that saves thousands and millions of lives, preserving and restoring their health.

Another option for using UV from a medical and biological point of view is the disinfection of rooms, the sterilization of work surfaces and tools. The action is based on the ability of UV to inhibit the development and replication of DNA molecules, which leads to their extinction. Bacteria, fungi, protozoa and viruses die.

The main problem when using such radiation for sterilization and disinfection of a room is the lighting area. After all, organisms are destroyed only by direct exposure to direct waves. Everything that remains outside continues to exist.

Analytical work with minerals

The ability to cause luminescence in substances allows the use of UV to analyze the qualitative composition of minerals and valuable rocks. In this regard, precious, semiprecious and ornamental stones are very interesting. What shades they do not give when irradiated with cathode waves! Very interesting about this wrote Malakhov, a famous geologist. His work tells about observations of the luminosity of the color palette, which minerals can give in different sources of radiation.

So, for example, topaz, which in the visible spectrum has a beautiful saturated blue color, is illuminated bright green when irradiated, and the emerald is red. Pearls cannot give any specific color at all and shimmers with multicolor. The result is simply fantastic.

If the studied rock contains uranium impurities, then the highlight will show a green color. Admixtures of melite give blue, and morganite - a lilac or pale purple hue.

Use in filters

Ultraviolet bactericidal radiation is also used for use in filters. The types of such structures may be different:

• solid;
• gaseous;
• liquid.

Such devices are mainly used in the chemical industry, in particular in chromatography. With their help, you can conduct a qualitative analysis of the composition of the substance and identify it by belonging to a particular class of organic compounds.

Drinking water treatment

Disinfection of drinking water with ultraviolet radiation is one of the most modern and high-quality methods for its purification from biological impurities. The advantages of this method are as follows:

• reliability;
• efficiency;
• lack of foreign products in the water;
• security;
• profitability;
• preservation of organoleptic properties of water.

That is why today such a disinfection technique keeps up with traditional chlorination. The action is based on the same features - the destruction of DNA of harmful living organisms in the water. Use UV with a wavelength of about 260 nm.

In addition to direct exposure to pests, ultraviolet is also used to destroy residues of chemical compounds that are used to soften and purify water: such as, for example, chlorine or chloramine.

Black light lamp

Such devices are equipped with special emitters capable of producing waves of great length, close to visible. However, they still remain indistinguishable to the human eye. Such lamps are used as devices that read secret signs from UV: for example, in passports, documents, banknotes and so on. That is, such marks can be distinguished only under the influence of a certain spectrum. Thus, the principle of operation of currency detectors, devices for checking the naturalness of banknotes is built.

Restoration and determination of the authenticity of the painting

And in this area UV is used. Each artist used whitewash containing various heavy metals in each epochal period of time. Thanks to irradiation, it is possible to obtain the so-called under-painting, which give information about the authenticity of the picture, as well as about the specific technique, the manner of writing of each artist.

In addition, the varnish film on the surface of the products refers to sensitive polymers. Therefore, it is able to age under the influence of light. This allows you to determine the age of compositions and masterpieces of the art world.