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;
• Visible part of the light, which is captured by the eye of man and animals (400-750 nm);
• Warm oxidizing (infrared) radiation (over 750 nm).

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

History of the discovery of UV radiation

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

It was possible to do this five centuries later, the physicist from Germany Ritter. It was he who conducted experiments on silver chloride on the decay of it under the influence of electromagnetic radiation. The scientist saw that this process is faster not in the area of light that was already open and was called infrared, but in the opposite direction. It turned out that this is a new field, which has not been investigated so far.

Thus, in 1842, ultraviolet radiation was discovered, the properties and applications of which were later subjected to careful analysis and study by different scientists. A great contribution to this was made by such people as Alexander Becquerel, Varshaver, Danzig, Macedonio Melloni, Frank, Parfenov, Galanin and others.

general characteristics

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

In physical nature, this is an electromagnetic wave, the length of which varies within fairly wide limits - from 10 (sometimes from 2) to 400 nm. The entire range of this radiation is conventionally divided into two regions:

1. Near spectrum. Comes to Earth through the atmosphere and the ozone layer from the Sun. The wavelength is 380-200 nm.
2. The Far (Vacuum). It is actively absorbed by ozone, air oxygen, atmospheric components. To investigate it is possible only by special vacuum devices, for what has received the name. The wavelength is 200-2 nm.

There is a classification of species that has ultraviolet radiation. Properties and applications find each of them.

1. Near.
2. Further.
3. Extreme.
4. Average.
5. Vacuum.
6. Long-wavelength black light (UV-A).
7. Shortwave germicidal (UV-C).
8. Medium-wave UV-B.

The wavelength of ultraviolet radiation for each species is different, but all of them are in general already designated earlier limits.

Interesting is UV-A, or, so-called, black light. The fact is that this spectrum has a wavelength of 400-315 nm. It is on the border with the visible light that the human eye can catch. 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 violet hue.

Spectra, which give sources of ultraviolet radiation, can be of three types:

• Ruled;
• Continuous;
• Molecular (striped).

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

Sources of ultraviolet radiation

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

• Natural or natural;
• Artificial, created by man;
• Laser.

The first group includes a single type of concentrator and a radiator - the Sun. It is the heavenly body that gives the most powerful charge of this type of waves, which are able to pass through the ozone layer and reach the surface of the Earth. However, not all of its mass. Scientists put forward the theory that life on Earth was born only when the ozone shield began to protect it from excessive penetration of harmful in large concentrations of UV radiation.

It was during this period that protein molecules, nucleic acids and ATP began to exist. Until now, the ozone layer comes into close interaction with the bulk of UV-A, UV-B and UV-C, neutralizing them, and preventing them from passing through themselves. Therefore protection from ultraviolet radiation of the whole planet is exclusively his merit.

What determines the concentration of ultraviolet penetrating to the Earth? There are several main factors:

• Ozone holes;
• height above sea level;
• Height of the solstice;
• Atmospheric dispersion;
• The degree of reflection of rays from terrestrial natural surfaces;
• The state of cloudy 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 given wavelength parameters. This was done in order to obtain ultraviolet radiation, the application of which can be extremely useful in various fields of activity. To artificial sources are:

1. Erythmic lamps, which have the ability to activate the synthesis of vitamin D in the skin. This protects against rickets and treats it.
2. Apparatus for solaria, in which people get not only a beautiful natural tan, but also are treated for diseases that occur when there is a lack of open sunlight (the so-called winter depression).
3. Lamps-attractants, which allow to fight insects in conditions of premises are safe for humans.
4. Mercury-quartz devices.
5. Excilamp.
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 can be:

• nitrogen;
• argon;
• neon;
• xenon;
• Organic scintillators;
• Crystals.

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

Biological effects on organisms

The effect of ultraviolet radiation on living beings is twofold. On the one hand, with its lack, diseases can arise. It turned out only at the beginning of the last century. Artificial irradiation with special UV-A in the required norms is capable of:

• To activate the work of immunity;
• Cause the formation of important vasodilator compounds (histamine, for example);
• Strengthen the musculoskeletal system;
• Improve the work of the lungs, increase the intensity of gas exchange;
• Affect the speed and quality of metabolism;
• Increase the tone of the body, activating the production of hormones;
• Increase the permeability of the walls of the vessels on the skin.

If UVA is in sufficient quantity to enter the human body, then it does not have such diseases as winter depression or light fasting, and the risk of developing rickets is significantly reduced.

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

• Bactericidal;
• Anti-inflammatory;
• Regenerating;
• Painkiller.

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

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

1. Skin cancer. This is the most dangerous exposure to ultraviolet radiation. Melanoma can form with the excessive influence of waves from any source - both natural and created by humans. This is especially true for sun lovers in the solarium. In all things, measure and caution is necessary.
2. Destructive effect on the retina of eyeballs. In other words, a cataract, a pterygium, or a shell burn can develop. The harmful excess UV exposure to the eyes has been proven by scientists for a long time and is confirmed by experimental data. Therefore, when working with such sources, you should follow the safety rules. On the street you can protect yourself with dark glasses. However, in this case, one should be afraid of fakes, because if the glasses are not equipped with UV-repelling filters, then the destructive effect will be even stronger.
3. Burns on the skin. In the summer, they can be earned if for a long time uncontrolled exposure to UV. In winter, you can get them because of the peculiarities of snow reflect almost completely these waves. Therefore, irradiation occurs both from the side of the Sun and from the side of the snow.
4. Aging. If people for a long time are under the influence of UV, then they begin very early to show signs of skin aging: lethargy, wrinkles, flabbiness. This is due to the fact that the protective barrier functions of the covers are weakened and broken.
5. Impact with consequences in time. Concluded in the manifestations of negative influences not at a young age, but closer to old age.

All these results are consequences of UV dosing, i.e. They arise when the use of ultraviolet radiation is carried out irrationally, incorrectly, and without observing safety measures.

Ultraviolet radiation: application

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

• High-level chemical activity;
• Bactericidal effect on organisms;
• The ability to cause the glow of various substances in different shades, the visible human eye (luminescence).

This makes it possible to widely use 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 certain type of UV with its own spectrum and wavelength. Recently, this type of radiation is actively used in physical and chemical studies (establishing the electronic configuration of atoms, the crystal structure of molecules and various compounds, working with ions, analyzing physical transformations at various space objects).

There is another peculiarity of the effect of UV on substances. Some polymer materials are able to 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 listed materials lose color, crack, fade and, eventually, are destroyed. Therefore, they are called sensitive polymers. This feature of the degradation of the carbon chain under conditions of solar illumination is actively used in nanotechnology, roentgenography, transplantology and other fields. This is done mainly to smooth out the roughness of the surface of the products.

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

Also, the use of ultraviolet germicidal radiation is carried out to attract and destroy insects. The action is based on the ability of the insect's eye to capture short-wave spectra invisible to man. Therefore, animals fly to the source, where they are subjected to destruction.

Use in solariums - special installations of vertical and horizontal type, in which the human body is exposed to UVA. This is done to activate the production in the skin of melanin, which gives it a darker color, smoothness. In addition, at the same time, inflammations are dried and harmful bacteria are destroyed on the surface of the integument. Particular attention should be paid to eye protection, sensitive areas.

Medical area

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 features that occur in the body during competent illumination by artificial or natural irradiation.

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

1. All kinds of inflammatory processes, open wounds, suppuration and open sutures.
2. With injuries of tissues, bones.
3. With burns, frostbite and skin diseases.
4. With respiratory ailments, tuberculosis, bronchial asthma.
5. In the emergence 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 ulcer of stomach.
9. Dental diseases.
10. Regulation of blood pressure, normalization of the heart.
11. Development of cancer tumors.
12. Atherosclerosis, kidney 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 people's lives, preserving and restoring their health.

Another option for using UV from a medical and biological point of view is disinfection of premises, sterilization of working 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 are dying.

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

Analytical work with minerals

The ability to cause luminescence in substances makes it possible to use UV to analyze the qualitative composition of minerals and valuable rocks. In this respect, precious, semiprecious and ornamental stones are very interesting. What kind of shades do they not give when irradiated with cathode waves? Very interesting about this wrote Malakhov, a famous geologist. In his work, he talks about observations of the glow of a color palette, which is capable of giving minerals in different sources of irradiation.

So, for example, topaz, which in the visible spectrum has a beautiful saturated blue color, when irradiated, bright green appears, and the emerald - red. Pearls generally can not give any specific color and overflow with multicolor. The spectacle as a result is simply fantastic.

If the composition of the studied rock includes uranium impurities, then the flashing will show a green color. The impurities of melitis are blue, and morganite is a lilac or pale purple hue.

Use in filters

For use in filters, ultraviolet bactericidal radiation is also used. Types of such structures can be different:

• Solid;
• Gaseous;
• Liquid.

The main application of such devices is found in the chemical industry, in particular, in chromatography. With their help, it is possible to conduct a qualitative analysis of the composition of a substance and to identify it as belonging to one or another class of organic compounds.

Treatment of drinking water

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

• reliability;
• efficiency;
• Absence of foreign products in the water;
• security;
• Economy;
• Preservation of organoleptic properties of water.

That is why to date, this method of disinfection is keeping pace with traditional chlorination. The action is based on the same features - the destruction of DNA of harmful living organisms in the water. UV is used with a wavelength of about 260 nm.

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

Black light bulb

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 reading 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 the work of currency detectors, devices for checking the naturalness of monetary denominations was constructed.

Restoration and determination of the authenticity of the painting

And in this area is used UV. Each artist used white, containing in each epochal interval of time different heavy metals. Thanks to irradiation, it is possible to receive so-called sub-masks, 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 lacquer film on the surface of the products refers to sensitive polymers. Therefore, it is able to grow old under the influence of light. This allows you to determine the age of compositions and masterpieces of the art world.