Infrared and ultraviolet radiation. Lesson "infrared, ultraviolet, x-ray radiation" for the specialty "welder"
Theoretically, the question How are infrared rays different from ultraviolet rays?' could be of interest to anyone. After all, both those and other rays are part of the solar spectrum - and we are exposed to the Sun every day. In practice, it is most often asked by those who are going to purchase devices known as infrared heaters, and would like to make sure that such devices are absolutely safe for human health.
How infrared rays differ from ultraviolet rays in terms of physics
As you know, in addition to seven visible colors spectrum beyond its limits, there are radiation invisible to the eye. In addition to infrared and ultraviolet, these include x-rays, gamma rays and microwaves. 
Infrared and UV rays are similar in one thing: they both belong to that part of the spectrum that is not visible to the naked eye of a person. But this is where their similarity ends.
Infrared radiation
Infrared rays were found outside the red border, between the long and short wavelengths of this part of the spectrum. It is worth noting that almost half of the solar radiation is infrared radiation. The main characteristic of these rays, invisible to the eye, is strong thermal energy: all heated bodies continuously radiate it.
Radiation of this type is divided into three regions according to such a parameter as wavelength:
- from 0.75 to 1.5 microns - near area;
- from 1.5 to 5.6 microns - medium;
- from 5.6 to 100 microns - far.
It must be understood that infrared radiation is not a product of all kinds of modern technical devices, for example, infrared heaters. This is a factor of the natural environment, which constantly acts on a person. Our body continuously absorbs and emits infrared rays.
Ultraviolet radiation
The existence of rays beyond the violet end of the spectrum was proved in 1801. The range of ultraviolet rays emitted by the Sun is from 400 to 20 nm, but only a small part of the short-wave spectrum reaches the earth's surface - up to 290 nm.
Scientists believe that ultraviolet radiation belongs to significant role in the formation of the first organic compounds on Earth. However, the impact of this radiation is also negative, leading to the decay of organic substances.
When answering a question, How is infrared radiation different from ultraviolet radiation?, it is necessary to consider the impact on the human body. And here the main difference lies in the fact that the effect of infrared rays is limited mainly to thermal effects, while ultraviolet rays can also have a photochemical effect.
UV radiation is actively absorbed by nucleic acids, resulting in changes in the most important indicators of cell vital activity - the ability to grow and divide. It is DNA damage that is the main component of the mechanism of exposure to ultraviolet rays on organisms.
The main organ of our body that is affected by ultraviolet radiation is the skin. It is known that thanks to UV rays, the process of formation of vitamin D, which is necessary for the normal absorption of calcium, is triggered, and serotonin and melatonin are also synthesized - important hormones that affect circadian rhythms and human mood.
Exposure to IR and UV radiation on the skin
When a person is exposed to sunlight, infrared, ultraviolet rays also affect the surface of his body. But the result of this impact will be different:
- IR rays cause a rush of blood to the surface layers of the skin, an increase in its temperature and redness (caloric erythema). This effect disappears as soon as the effect of irradiation stops.
- Exposure to UV radiation has a latent period and may appear several hours after exposure. The duration of ultraviolet erythema ranges from 10 hours to 3-4 days. The skin turns red, may peel off, then its color becomes darker (tan).
It has been proven that excessive exposure to ultraviolet radiation can lead to the occurrence of malignant skin diseases. At the same time, in certain doses, UV radiation is beneficial for the body, which allows it to be used for prevention and treatment, as well as for the destruction of bacteria in indoor air.
Is infrared radiation safe?
People's fears in relation to such a type of device as infrared heaters are quite understandable. IN modern society a steady tendency has already formed with a fair amount of fear to treat many types of radiation: radiation, x-rays, etc.
For ordinary consumers who are going to purchase devices based on the use of infrared radiation, the most important thing to know is the following: infrared rays are completely safe for human health. This is what needs to be emphasized when considering How are infrared rays different from ultraviolet rays?.
Studies have proven that long-wave infrared radiation is not only useful for our body - it is absolutely necessary for it. With a lack of infrared rays, the body's immunity suffers, and the effect of its accelerated aging is also manifested. 
The positive impact of infrared radiation is no longer in doubt and manifests itself in various aspects.
Ust-Kamenogorsk College of Construction
Development of a lesson in physics.
Topic: "Infrared, ultraviolet, x-ray radiation"
Lecturer: O.N. Chirtsova
Ust-Kamenogorsk, 2014
Lesson on the topic "Infrared, ultraviolet, x-rays."
Goals:1) know what infrared, ultraviolet, x-ray radiation is; be able to solve logical problems on the application of these concepts.
2) development logical thinking, observation, PMD (analysis, synthesis, comparison), skills of working on a concept (its lexical meaning), speech, OUUN (independent work with a source of information, building a table).
3) the formation of a scientific outlook (practical significance of the material being studied, connection with the profession), responsibility, independence, the need to conduct healthy lifestyle life, comply with TB standards in professional activities.
Lesson type: learning new material
Type of lesson: theoretical study
Equipment: laptops, projector, presentation, welder's overalls
Literature: Krongart B.A. "Physics-11", INTERNET materials
During the classes.
Organization of students for class.
Preparing for perception.
I draw students' attention to the welder's overalls hanging in front of them, build a conversation on the following questions:
1) What material is the workwear made from? (rubberized fabric, suede) Why from these materials? (I lead students to the answer “protection from thermal (infrared) radiation)”
2) What is the mask for? (UV protection).
3) The main result in the work of the welder? (seam quality) How can the quality of the weld be examined? (one of the methods is x-ray flaw detection). On the slide I show a photo of the x-ray unit and briefly explain the method.
I announce the topic of the lesson (write in a notebook).
Students formulate the purpose of the lesson.
I set tasks for the students for the lesson:
1) Get to know common characteristic radiation (according to the position on the scale electromagnetic radiation).
2) Get acquainted with the general characteristics of each type of radiation.
3) Investigate in detail each type of radiation.
We carry out the first task of the lesson - we get acquainted with the general characteristics of radiation.
Learning new material.
On the slide "Scale of electromagnetic radiation". We determine the position of each type of radiation on the scale, analyze the lexical meaning of the words "infrared", "ultraviolet", "X-ray". I support with examples.
So, we have completed the first task of the lesson, we move on to the second task - we get acquainted with the general characteristics of each type of radiation. (I show videos about each type of radiation. After watching, I build a short conversation on the content of the videos).
So, let's move on to the third task of the lesson - the study of each type of radiation.
Students do it on their own research work(using a digital source of information, fill out the table). I announce evaluation criteria, regulations. I advise and explain the issues that have arisen in the course of work.
At the end of the work, we listen to the answers of three students, review the answers.
Anchoring.
Orally we solve logical problems:
1. Why is it necessary to wear dark glasses high in the mountains?
2. What kind of radiation is used for drying fruits and vegetables?
Why does a welder wear a mask while welding? protective suit?
Why is barium porridge given to a patient before X-ray examination?
Why do the radiologist (as well as the patient) wear lead aprons?
An occupational disease of welders is cataract (clouding of the lens of the eye). What causes it? (long-term thermal IR radiation) How to avoid?
Electrophthalmia is an eye disease (accompanied by acute pain, pain in the eyes, lacrimation, eyelid spasms). The cause of this disease? (action of UV radiation). How to avoid?
Reflection.
Students answer the following questions in writing:
What was the purpose of the lesson?
Where are the studied types of radiation used?
What harm can they do?
Where will the knowledge acquired in the lesson be useful in your profession?
Orally we discuss the answers to these questions, the sheets are handed over.
Homework
Prepare a report on practical application IR, UV, X-ray (optional).
Summary of the lesson.
Students hand over notebooks.
I announce grades for the lesson.
Handout.
Infrared radiation.
Infrared radiation - electromagnetic radiation occupying the spectral region between the red end visible light and microwave radiation.
The optical properties of substances in infrared radiation differ significantly from their properties in visible radiation. For example, a water layer of several centimeters is opaque to infrared radiation with λ = 1 µm. Infrared radiation makes up most of the radiationincandescent lamps, gas discharge lamps, about 50% of solar radiation; infrared radiation emitted by some lasers. To register it, they use thermal and photoelectric receivers, as well as special photographic materials.
The entire range of infrared radiation is divided into three components:
shortwave region: λ = 0.74-2.5 µm;
medium wave region: λ = 2.5-50 µm;
longwave region: λ = 50-2000 µm.
The long-wave edge of this range is sometimes distinguished into a separate range of electromagnetic waves - terahertz radiation (submillimeter radiation).
Infrared radiation is also called "thermal" radiation, since infrared radiation from heated objects is perceived by human skin as a sensation of warmth. In this case, the wavelengths emitted by the body depend on the heating temperature: the higher the temperature, the shorter the wavelength and the higher the radiation intensity. The radiation spectrum of an absolutely black body at relatively low (up to several thousand Kelvin) temperatures lies mainly in this range. Infrared radiation is emitted by excited atoms or ions.
Application.
Night-vision device.
A vacuum photoelectronic device for converting an image of an object invisible to the eye (in the infrared, ultraviolet or X-ray spectrum) into a visible one or to enhance the brightness of the visible image.
Thermography.
Infrared thermography, thermal image or thermal video, is a scientific way of obtaining a thermogram - an image in infrared rays that shows a picture of the distribution of temperature fields. Thermographic cameras or thermal imagers detect radiation in the infrared range of the electromagnetic spectrum (approximately 900-14000 nanometers or 0.9-14 µm) and, based on this radiation, create images that allow you to determine overheated or supercooled places. Since infrared radiation is emitted by all objects that have a temperature, according to Planck's formula for black body radiation, thermography allows you to "see" environment with or without visible light. The amount of radiation emitted by an object increases as its temperature rises, so thermography allows us to see differences in temperature. When we look through a thermal imager, warm objects are seen better than those cooled to ambient temperature; humans and warm-blooded animals are more easily visible in the environment, both during the day and at night. As a result, the promotion of the use of thermography can be attributed to the military and security services.
Infrared homing.
Infrared homing head - a homing head that works on the principle of capturing infrared waves emitted by the target being captured. It is an optical-electronic device designed to identify a target against the surrounding background and issue a capture signal to the automatic sighting device (APU), as well as to measure and issue a signal of the angular velocity of the line of sight to the autopilot.
Infrared heater.
heating appliance, which gives off heat to the environment through infrared radiation. In everyday life, it is sometimes inaccurately called a reflector. Radiant energy is absorbed by surrounding surfaces, turning into thermal energy, heats them, which in turn give off heat to the air. This gives a significant economic effect compared to convection heating, where heat is significantly spent on heating the unused subceiling space. In addition, with the help of IR heaters, it becomes possible to heat locally only those areas in the room where it is necessary without heating the entire volume of the room; the thermal effect of infrared heaters is felt immediately after switching on, which avoids preheating the room. These factors reduce energy costs.
Infrared astronomy.
Branch of astronomy and astrophysics that studies space objects visible in infrared radiation. In this case, infrared radiation means electromagnetic waves with a wavelength from 0.74 to 2000 microns. Infrared radiation is in the range between visible radiation, whose wavelength ranges from 380 to 750 nanometers, and submillimeter radiation.
Infrared astronomy began to develop in the 1830s, several decades after the discovery of infrared radiation by William Herschel. Initially, little progress was made and until the early 20th century there were no discoveries of astronomical objects in the infrared other than the Sun and Moon, but after a series of discoveries made in radio astronomy in the 1950s and 1960s, astronomers realized the presence of a large amount of information that was outside the visible range. waves. Since then, modern infrared astronomy has been formed.
infrared spectroscopy.
Infrared spectroscopy - a branch of spectroscopy covering the long wavelength region of the spectrum (> 730 nm beyond the red limit of visible light). Infrared spectra arise as a result of the vibrational (partly rotational) motion of molecules, namely, as a result of transitions between vibrational levels of the ground electronic state of molecules. IR radiation is absorbed by many gases, with the exception of such as O2, N2, H2, Cl2 and monatomic gases. Absorption occurs at a wavelength characteristic of each specific gas, for CO, for example, this is the wavelength of 4.7 microns.
Using infrared absorption spectra, one can establish the structure of molecules of various organic (and inorganic) substances with relatively short molecules: antibiotics, enzymes, alkaloids, polymers, complex compounds, etc. Vibrational spectra of molecules of various organic (and inorganic) substances with relatively long molecules (proteins, fats, carbohydrates, DNA, RNA, etc.) are in the terahertz range, so the structure of these molecules can be established using radio frequency spectrometers in the terahertz range. By the number and position of the peaks in the IR absorption spectra, one can judge the nature of the substance (qualitative analysis), and by the intensity of the absorption bands, the amount of the substance (quantitative analysis). The main instruments are various types of infrared spectrometers.
infrared channel.
An infrared channel is a data transmission channel that does not require wired connections for its operation. In computer technology, it is usually used to connect computers with peripheral devices (IrDA interface). Unlike the radio channel, the infrared channel is insensitive to electromagnetic interference, and this allows it to be used in industrial conditions. The disadvantages of the infrared channel include the high cost of receivers and transmitters, which require the conversion of an electrical signal into infrared and vice versa, as well as low transmission rates (usually does not exceed 5-10 Mbps, but when using infrared lasers, significantly higher speeds are possible). In addition, the confidentiality of the transmitted information is not ensured. In line-of-sight conditions, an infrared channel can provide communication over distances of several kilometers, but it is most convenient for connecting computers located in the same room, where reflections from the walls of the room provide a stable and reliable connection. The most natural type of topology here is the "bus" (that is, the transmitted signal is simultaneously received by all subscribers). It is clear that with so many shortcomings, the infrared channel could not be widely used.
Medicine
Infrared rays are used in physiotherapy.
Remote control
Infrared diodes and photodiodes are widely used in remote controls, automation systems, security systems, some mobile phones (infrared port), etc. Infrared rays do not distract a person's attention due to their invisibility.
Interestingly, the infrared radiation of a household remote control is easily captured using a digital camera.
When painting
Infrared emitters are used in industry for drying paint surfaces. The infrared drying method has significant advantages over the traditional, convection method. First of all, this is, of course, an economic effect. The speed and energy expended with infrared drying is less than those with traditional methods.
Food sterilization
Sterilized using infrared radiation food products for the purpose of disinfection.
Anti-corrosion agent
Infra-red rays are used to prevent corrosion of varnished surfaces.
food industry
A feature of the use of IR radiation in Food Industry is the possibility of penetration of an electromagnetic wave into such capillary-porous products as grain, cereals, flour, etc. to a depth of up to 7 mm. This value depends on the nature of the surface, structure, properties of the material and the frequency response of the radiation. An electromagnetic wave of a certain frequency range has not only a thermal, but also a biological effect on the product, it helps to accelerate biochemical transformations in biological polymers (starch, protein, lipids). Conveyor drying conveyors can be successfully used when laying grain in granaries and in the flour-grinding industry.
In addition, infrared radiation is widely used forspace heating And streetspaces. Infrared heaters are used to organize additional or main heating in premises (houses, apartments, offices, etc.), as well as for local heating of outdoor space (street cafes, gazebos, verandas).
The disadvantage is the significantly greater non-uniformity of heating, which is completely unacceptable in a number of technological processes.
Checking money for authenticity
The infrared emitter is used in devices for checking money. Applied to the banknote as one of the security elements, special metameric inks can only be seen in the infrared range. Infrared currency detectors are the most error-free devices for checking money for authenticity. Applying infrared tags to banknotes, unlike ultraviolet ones, is expensive for counterfeiters and therefore economically unprofitable. Therefore, banknote detectors with a built-in IR emitter, today, are the most reliable protection from fakes.
Health hazard!!!
Very strong infrared radiation in places of high heat can dry out the mucous membrane of the eyes. It is most dangerous when the radiation is not accompanied by visible light. In such situations, it is necessary to wear special protective goggles for the eyes.
Earth as an infrared emitter
The Earth's surface and clouds absorb visible and invisible radiation from the sun and re-radiate most of the energy in the form of infrared radiation back into the atmosphere. Certain substances in the atmosphere, mainly water droplets and water vapor, but also carbon dioxide, methane, nitrogen, sulfur hexafluoride and chlorofluorocarbons, absorb this infrared radiation and re-radiate it in all directions, including back to Earth. Thus, the greenhouse effect keeps the atmosphere and surface warmer than if there were no infrared absorbers in the atmosphere.
x-ray radiation
X-ray radiation - electromagnetic waves, the photon energy of which lies on the electromagnetic wave scale between ultraviolet radiation and gamma radiation, which corresponds to wavelengths from 10−2 to 102 Å (from 10−12 to 10−8 m)
Laboratory sources
X-ray tubes
X-rays are produced by strong acceleration of charged particles (bremsstrahlung), or by high-energy transitions in the electron shells of atoms or molecules. Both effects are used in X-ray tubes. The main structural elements of such tubes are a metal cathode and an anode (previously also called an anticathode). In x-ray tubes, electrons emitted from the cathode are accelerated by the difference in electrical potential between the anode and cathode (no x-rays are emitted because the acceleration is too low) and hit the anode, where they are abruptly decelerated. In this case, X-ray radiation is generated due to bremsstrahlung, and electrons are simultaneously knocked out of the inner electron shells of the anode atoms. Empty spaces in the shells are occupied by other electrons of the atom. In this case, X-ray radiation is emitted with an energy spectrum characteristic of the anode material (characteristic radiation, frequencies are determined by Moseley's law: where Z is the atomic number of the anode element, A and B are constants for a certain value of the principal quantum number n of the electron shell). At present, anodes are made mainly of ceramics, and the part where the electrons hit is made of molybdenum or copper.
Crookes tube
In the process of acceleration-deceleration, only about 1% of the kinetic energy of an electron goes to X-rays, 99% of the energy is converted into heat.
Particle accelerators
X-rays can also be obtained in particle accelerators. The so-called synchrotron radiation occurs when a beam of particles in a magnetic field is deflected, as a result of which they experience acceleration in a direction perpendicular to their movement. Synchrotron radiation has a continuous spectrum with an upper limit. With appropriately chosen parameters (the magnitude of the magnetic field and the energy of the particles), X-rays can also be obtained in the spectrum of synchrotron radiation.
Biological impact
X-rays are ionizing. It affects the tissues of living organisms and can cause radiation sickness, radiation burns, and malignant tumors. For this reason, protective measures must be taken when working with X-rays. It is believed that the damage is directly proportional to the absorbed dose of radiation. X-ray radiation is a mutagenic factor.
Registration
Luminescence effect. X-rays can cause some substances to glow (fluorescence). This effect is used in medical diagnostics during fluoroscopy (observation of an image on a fluorescent screen) and X-ray photography (radiography). Medical photographic films are usually used in combination with intensifying screens, which include X-ray phosphors, which glow under the action of X-rays and illuminate the light-sensitive photographic emulsion. Image Acquisition Method life size called radiography. With fluorography, the image is obtained on a reduced scale. The luminescent substance (scintillator) can be optically connected to an electronic light detector (photomultiplier tube, photodiode, etc.), the resulting device is called a scintillation detector. It allows you to register individual photons and measure their energy, since the energy of a scintillation flash is proportional to the energy of an absorbed photon.
photographic effect. X-rays, as well as ordinary light, are able to directly illuminate the photographic emulsion. However, without the fluorescent layer, this requires 30-100 times the exposure (i.e. dose). This method (known as screenless radiography) has the advantage of sharper images.
In semiconductor detectors, X-rays produce electron-hole pairs in the p-n junction of a diode connected in the blocking direction. In this case, a small current flows, the amplitude of which is proportional to the energy and intensity of the incident X-ray radiation. In the pulsed mode, it is possible to register individual X-ray photons and measure their energy.
Individual X-ray photons can also be registered using gas-filled detectors of ionizing radiation (Geiger counter, proportional chamber, etc.).
Application
With the help of X-rays, it is possible to "enlighten" the human body, as a result of which it is possible to obtain an image of the bones, and in modern instruments, of the internal organs (see alsoradiography And fluoroscopy). This uses the fact that the element calcium (Z=20) contained mainly in the bones has an atomic number much larger than the atomic numbers of the elements that make up soft tissues, namely hydrogen (Z=1), carbon (Z=6) , nitrogen (Z=7), oxygen (Z=8). In addition to conventional devices that give a two-dimensional projection of the object under study, there are computed tomographs that allow you to obtain a three-dimensional image of the internal organs.
The detection of defects in products (rails, welds, etc.) using X-rays is calledx-ray flaw detection.
In materials science, crystallography, chemistry and biochemistry, X-rays are used to elucidate the structure of substances at the atomic level using X-ray diffraction scattering (x-ray diffraction analysis). A famous example is the determination of the structure of DNA.
X-rays can be used to determine chemical composition substances. In an electron beam microprobe (or in an electron microscope), the analyzed substance is irradiated with electrons, while the atoms are ionized and emit characteristic x-ray radiation. X-rays can be used instead of electrons. This analytical method is calledX-ray fluorescence analysis.
Airports are actively usingx-ray television introscopes, allowing you to view the contents of hand luggage and baggage in order to visual detection on the monitor screen of dangerous items.
X-ray therapy- a section of radiotherapy covering theory and practice therapeutic use x-rays generated at a voltage on the X-ray tube of 20-60 kV and a skin-focal distance of 3-7 cm (short-range radiotherapy) or at a voltage of 180-400 kV and a skin-focal distance of 30-150 cm (remote radiotherapy). X-ray therapy is carried out mainly with superficially located tumors and with some other diseases, including skin diseases (ultrasoft X-rays of Bucca).
natural x-rays
On Earth, electromagnetic radiation in the X-ray range is formed as a result of ionization of atoms by radiation that occurs during radioactive decay, as a result of the Compton effect of gamma radiation that occurs during nuclear reactions, as well as cosmic radiation. Radioactive decay also leads to direct emission of X-ray quanta if it causes a rearrangement of the electron shell of the decaying atom (for example, during electron capture). X-ray radiation that occurs on other celestial bodies, does not reach the surface of the Earth, as it is completely absorbed by the atmosphere. It is being explored by satellite X-ray telescopes such as Chandra and XMM-Newton.
One of the main methods of non-destructive testing is the radiographic method of control (RK) -x-ray flaw detection. This type of control is widely used to check the quality of technological pipelines, metal structures, technological equipment, composite materials in various industries and the construction complex. X-ray control is actively used today to detect various defects in welds and joints. The radiographic method of testing welded joints (or X-ray flaw detection) is carried out in accordance with the requirements of GOST 7512-86.
The method is based on the different absorption of X-rays by materials, and the degree of absorption directly depends on the atomic number of the elements and the density of the medium of a particular material. The presence of defects such as cracks, inclusions of foreign materials, slags and pores leads to the fact that X-rays are attenuated to one degree or another. By registering their intensity using X-ray control, it is possible to determine the presence, as well as the location of various material inhomogeneities.
Main features of X-ray control:
The ability to detect such defects that cannot be detected by any other method - for example, non-solders, shells and others;
Possibility of exact localization of the detected defects, which makes it possible to quickly repair;
The possibility of assessing the magnitude of the convexity and concavity of the weld reinforcing beads.
UV radiation
Ultraviolet radiation (ultraviolet rays, UV radiation) - electromagnetic radiation occupying the spectral range between visible and x-ray radiation. Wavelengths of UV radiation lie in the range from 10 to 400 nm (7.5 1014-3 1016 Hz). The term comes from lat. ultra - above, beyond and purple. IN colloquial speech the name "ultraviolet" may also be used.
Impact on human health .
The biological effects of ultraviolet radiation in the three spectral regions are significantly different, so biologists sometimes distinguish the following ranges as the most important in their work:
Near ultraviolet, UV-A rays (UVA, 315-400 nm)
UV-B rays (UVB, 280-315 nm)
Far ultraviolet, UV-C rays (UVC, 100-280nm)
Virtually all UVC and approximately 90% UVB are absorbed by ozone as well as water vapour, oxygen and carbon dioxide as sunlight passes through earth's atmosphere. Radiation from the UVA range is rather weakly absorbed by the atmosphere. Therefore, the radiation that reaches the Earth's surface contains a large part of the near ultraviolet UVA and a small proportion - UVB.
Somewhat later, in the works (O. G. Gazenko, Yu. E. Nefedov, E. A. Shepelev, S. N. Zaloguev, N. E. Panferova, I. V. Anisimova), the specified specific effect of radiation was confirmed in space medicine . Prophylactic UV irradiation was introduced into the practice of space flights along with the Guidelines (MU) 1989 "Prophylactic ultraviolet irradiation of people (using artificial sources of UV radiation)" . Both documents are a reliable basis for further improvement of UV prevention.
Action on the skin
Skin exposure to ultraviolet radiation that exceeds the skin's natural protective ability to tan leads to burns.
Ultraviolet radiation can lead to the formation of mutations (ultraviolet mutagenesis). The formation of mutations, in turn, can cause skin cancer, skin melanoma and premature aging.
Action on the eyes
Ultraviolet radiation of the medium wave range (280-315 nm) is practically imperceptible to the human eye and is mainly absorbed by the corneal epithelium, which, with intense irradiation, causes radiation damage - corneal burns (electrophthalmia). This is manifested by increased lacrimation, photophobia, edema of the corneal epithelium, blepharospasm. As a result of a pronounced reaction of the eye tissues to ultraviolet, the deep layers (corneal stroma) are not affected, since the human body reflexively eliminates the effects of ultraviolet on the organs of vision, only the epithelium is affected. After the regeneration of the epithelium, vision, in most cases, is completely restored. Soft long-wave ultraviolet (315-400 nm) is perceived by the retina as a weak violet or grayish-blue light, but is almost completely retained by the lens, especially in middle-aged and elderly people. Patients implanted with early artificial lenses began to see ultraviolet light; modern samples of artificial lenses do not let ultraviolet through. Shortwave ultraviolet (100-280 nm) can penetrate to the retina. Since ultraviolet short-wave radiation is usually accompanied by ultraviolet radiation of other ranges, with intense exposure to the eyes, a corneal burn (electrophthalmia) will occur much earlier, which will exclude the effect of ultraviolet radiation on the retina for the above reasons. In clinical ophthalmological practice, the main type of eye damage caused by ultraviolet radiation is corneal burn (electrophthalmia).
Eye protection
To protect the eyes from the harmful effects of ultraviolet radiation, special goggles are used that block up to 100% of ultraviolet radiation and are transparent in the visible spectrum. As a rule, the lenses of such glasses are made of special plastics or polycarbonate.
Many types of contact lenses also offer 100% UV protection (look at the package label).
Filters for ultraviolet rays are solid, liquid and gaseous. For example, ordinary glass is opaque at λ< 320 нм; в более коротковолновой области прозрачны лишь специальные сорта стекол (до 300-230 нм), кварц прозрачен до 214 нм, флюорит - до 120 нм. Для еще более коротких волн нет подходящего по прозрачности материала для линз объектива и приходится применять отражательную оптику - вогнутые зеркала. Однако для столь короткого ультрафиолета непрозрачен уже и воздух, который заметно поглощает ультрафиолет, начиная с 180 нм.
UV Sources
natural springs
The main source of ultraviolet radiation on Earth is the Sun. The ratio of UV-A to UV-B radiation intensity, the total amount of ultraviolet rays reaching the Earth's surface, depends on the following factors:
on the concentration of atmospheric ozone above the earth's surface (see ozone holes)
from the height of the sun above the horizon
from height above sea level
from atmospheric dispersion
from cloud cover
on the degree of reflection of UV rays from the surface (water, soil)
Two ultraviolet fluorescent lamps, both lamps emit "long wavelength" (UV-A) wavelengths ranging from 350 to 370 nm
A DRL lamp without a bulb is a powerful source of ultraviolet radiation. Hazardous to eyes and skin during operation.
artificial sources
Thanks to the creation and improvement of artificial sources of UV radiation, which went in parallel with the development electrical sources visible light, today specialists working with UV radiation in medicine, preventive, sanitary and hygienic institutions, agriculture, etc., are provided with significantly greater opportunities than when using natural UV radiation. The development and production of UV lamps for photobiological installations (UFBD) is currently carried out by a number of the largest electric lamp companies and others. In contrast to lighting sources, UV radiation sources, as a rule, have a selective spectrum designed to achieve maximum possible effect for a specific FB process. Classification of artificial UV IS by areas of application, determined through the action spectra of the corresponding FB processes with certain UV spectral ranges:
Erythema lamps were developed in the 1960s to compensate for the “UV deficiency” of natural radiation and, in particular, to intensify the process of photochemical synthesis of vitamin D3 in human skin (“anti-rachitis effect”).
In the 1970s and 1980s, erythema LLs, in addition to medical institutions, were used in special “fotaria” (for example, for miners and mining workers), in separate public and industrial buildings northern regions, as well as for irradiating young farm animals.
The LE30 spectrum is radically different from the solar spectrum; region B accounts for most of the radiation in the UV region, radiation with a wavelength λ< 300нм, которое в естественных условиях вообще отсутствует, может достигать 20 % от общего УФ излучения. Обладая хорошим «антирахитным действием», излучение эритемных ламп с максимумом в диапазоне 305-315 нм оказывает одновременно сильное повреждающее воздействие на коньюктиву (слизистую оболочку глаза). Отметим, что в номенклатуре УФ ИИ фирмы Philips присутствуют ЛЛ типа TL12 с предельно близкими к ЛЭ30 спектральными характеристиками, которые наряду с более «жесткой» УФ ЛЛ типа TL01 используются в медицине для лечения фотодерматозов. Диапазон существующих УФ ИИ, которые используются в фототерапевтических установках, достаточно велик; наряду с указанными выше УФ ЛЛ, это лампы типа ДРТ или специальные МГЛ зарубежного производства, но с обязательной фильтрацией УФС излучения и ограничением доли УФВ либо путем легирования кварца, либо с помощью специальных светофильтров, входящих в комплект облучателя.
In the countries of Central and Northern Europe, as well as in Russia, there is enough wide use received UV DUs of the “Artificial solarium” type, in which UV LLs are used, causing a fairly rapid formation of a tan. In the spectrum of "tanning" UV LL, "soft" radiation in the UVA zone prevails. The share of UVB is strictly regulated, depends on the type of installations and skin type (in Europe, there are 4 types of human skin from "Celtic" to "Mediterranean") and is 1-5% from total UV radiation. LLs for tanning are available in standard and compact versions with power from 15 to 160 W and length from 30 to 180 cm.
In 1980, the American psychiatrist Alfred Levy described the effect of "winter depression", which is now classified as a disease and is abbreviated as SAD (Seasonal Affective Disorder - Seasonal Affective Disorder). The disease is associated with insufficient insolation, that is, natural lighting. According to experts, ~ 10-12% of the world's population is affected by SAD syndrome, and primarily residents of the countries of the Northern Hemisphere. Data for the USA are known: in New York - 17%, in Alaska - 28%, even in Florida - 4%. For the Nordic countries, data range from 10 to 40%.
Due to the fact that SAD is undoubtedly one of the manifestations of "solar failure", a return of interest to the so-called "full spectrum" lamps is inevitable, which accurately reproduces the spectrum of natural light not only in the visible, but also in the UV region. Row foreign firms included a full spectrum LL in its nomenclature, for example, Osram and Radium produce similar UV IS with a power of 18, 36 and 58 W under the names, respectively, "Biolux" and "Biosun", the spectral characteristics of which are almost the same. These lamps, of course, do not have an "anti-rachitic effect", but they help to eliminate a number of adverse syndromes in people associated with poor health in the autumn-winter period and can also be used for preventive purposes in educational institutions, schools, kindergartens, enterprises and institutions to compensate" light starvation. At the same time, it should be recalled that LLs of “full spectrum” compared to LLs of chromaticity LBs have a luminous efficiency approximately 30% less, which will inevitably lead to an increase in energy and capital costs in the lighting and irradiation installation. Such installations must be designed and operated in accordance with the requirements of CTES 009/E:2002 "Photobiological safety of lamps and lamp systems".
A very rational use was found for UFLL, the emission spectrum of which coincides with the phototaxis action spectrum of some types of flying insect pests (flies, mosquitoes, moths, etc.), which can be carriers of diseases and infections, lead to spoilage of products and products.
These UV LLs are used as attractant lamps in special light traps installed in cafes, restaurants, food industry enterprises, livestock and poultry farms, clothing warehouses, etc.
Mercury-quartz lamp
Fluorescent lamps "daylight" (have a small UV component from the mercury spectrum)
Excilamp
Light-emitting diode
Electric arc ionization process (In particular, the process of welding metals)
Laser sources
There are a number of lasers operating in the ultraviolet region. The laser makes it possible to obtain coherent radiation of high intensity. However, the ultraviolet region is difficult for laser generation, so there are no sources as powerful here as in the visible and infrared ranges. Ultraviolet lasers find their application in mass spectrometry, laser microdissection, biotechnology and others. scientific research, in eye microsurgery (LASIK), for laser ablation.
As an active medium in ultraviolet lasers, either gases (for example, an argon laser, a nitrogen laser, an excimer laser, etc.), condensed inert gases, special crystals, organic scintillators, or free electrons propagating in an undulator can be used.
There are also ultraviolet lasers that use the effects of non-linear optics to generate the second or third harmonic in the ultraviolet range.
In 2010, a free electron laser was demonstrated for the first time, generating coherent photons with an energy of 10 eV (the corresponding wavelength is 124 nm), that is, in the vacuum ultraviolet range.
Degradation of polymers and dyes
Many polymers used in consumer products degrade when exposed to UV light. To prevent degradation, special substances capable of absorbing UV are added to such polymers, which is especially important when the product is exposed to direct sunlight. The problem manifests itself in the disappearance of color, tarnishing of the surface, cracking, and sometimes the complete destruction of the product itself. The rate of destruction increases with increasing time of exposure and intensity of sunlight.
The described effect is known as UV aging and is one of the varieties of polymer aging. Sensitive polymers include thermoplastics such as polypropylene, polyethylene, polymethyl methacrylate (organic glass) as well as special fibers such as aramid fiber. UV absorption leads to the destruction of the polymer chain and loss of strength at a number of points in the structure. The action of UV on polymers is used in nanotechnologies, transplantation, X-ray lithography, and other fields to modify the properties (roughness, hydrophobicity) of the surface of polymers. For example, the smoothing effect of vacuum ultraviolet (VUV) on the surface of polymethyl methacrylate is known.
Scope of application
Black light
On credit VISA cards when illuminated with UV rays, an image of a soaring dove appears
A black light lamp is a lamp that emits predominantly in the long wavelength ultraviolet region of the spectrum (UVA range) and produces very little visible light.
To protect documents from counterfeiting, they are often provided with UV labels that are only visible under UV light conditions. Most passports, as well as banknotes of various countries, contain security elements in the form of paint or threads that glow in ultraviolet light.
The ultraviolet radiation emitted by black light lamps is quite mild and has the least severe Negative influence on human health. However, when using these lamps in dark room there is some danger associated precisely with insignificant radiation in the visible spectrum. This is due to the fact that in the dark the pupil expands and a relatively large part of the radiation freely enters the retina.
Sterilization by ultraviolet radiation
Disinfection of air and surfaces
Quartz lamp used for sterilization in the laboratory
Ultraviolet lamps are used for sterilization (disinfection) of water, air and various surfaces in all spheres of human activity. In the most common low-pressure lamps, almost the entire emission spectrum falls at a wavelength of 253.7 nm, which is in good agreement with the peak of the bactericidal efficacy curve (that is, the efficiency of UV absorption by DNA molecules). This peak is around the wavelength of 253.7 nm, which has the greatest effect on DNA, but natural substances (eg water) delay UV penetration.
Germicidal UV radiation at these wavelengths causes dimerization of thymine in DNA molecules. The accumulation of such changes in the DNA of microorganisms leads to a slowdown in their reproduction and extinction. Germicidal ultraviolet lamps are mainly used in devices such as bactericidal irradiators and bactericidal recirculators.
Ultraviolet treatment of water, air and surfaces does not have a prolonged effect. The advantage of this feature is that harmful effects on humans and animals are excluded. In the case of wastewater treatment with UV, the flora of water bodies is not affected by discharges, as, for example, with the discharge of water treated with chlorine, which continues to destroy life long after use in the treatment plant.
Ultraviolet lamps with a bactericidal effect in everyday life are often referred to simply as bactericidal lamps. Quartz lamps also have a bactericidal effect, but their name is not due to the effect of action, as in bactericidal lamps, but is associated with the material of the lamp bulb - quartz glass.
Drinking water disinfection
Disinfection of water is carried out by the method of chlorination in combination, as a rule, with ozonation or disinfection with ultraviolet (UV) radiation. Ultraviolet (UV) disinfection is a safe, economical and effective method of disinfection. Neither ozonation nor ultraviolet radiation has a bactericidal aftereffect, therefore they are not allowed to be used as independent means of water disinfection in the preparation of water for drinking water supply, for swimming pools. Ozonation and ultraviolet disinfection are used as additional methods of disinfection, together with chlorination, increase the efficiency of chlorination and reduce the amount of added chlorine-containing reagents.
The principle of operation of UV radiation. UV disinfection is performed by irradiating microorganisms in water with UV radiation of a certain intensity (a sufficient wavelength for the complete destruction of microorganisms is 260.5 nm) for a certain period of time. As a result of such irradiation, microorganisms "microbiologically" die, as they lose their ability to reproduce. UV radiation in the wavelength range of about 254 nm penetrates well through water and the cell wall of a water-borne microorganism and is absorbed by the DNA of microorganisms, causing damage to its structure. As a result, the process of reproduction of microorganisms stops. It should be noted that this mechanism extends to living cells of any organism as a whole, and this is precisely what causes the danger of hard ultraviolet radiation.
Although UV treatment is several times inferior to ozonation in terms of the effectiveness of water disinfection, today the use of UV radiation is one of the most effective and safe ways disinfection of water in cases where the volume of treated water is small.
Currently, in developing countries, in regions experiencing a lack of clean drinking water, the method of water disinfection by sunlight (SODIS) is being introduced, in which the ultraviolet component of solar radiation plays the main role in purifying water from microorganisms.
Chemical analysis
UV spectrometry
UV spectrophotometry is based on irradiating a substance with monochromatic UV radiation, the wavelength of which changes with time. Substance in varying degrees absorbs UV radiation with different wavelengths. The graph, on the y-axis of which the amount of transmitted or reflected radiation is plotted, and on the abscissa - the wavelength, forms a spectrum. The spectra are unique for each substance; this is the basis for the identification of individual substances in a mixture, as well as their quantitative measurement.
Mineral analysis
Many minerals contain substances that, when illuminated with ultraviolet radiation, begin to emit visible light. Each impurity glows in its own way, which makes it possible to determine the composition of a given mineral by the nature of the glow. A. A. Malakhov in his book “Interesting about Geology” (M., “Molodaya Gvardiya”, 1969. 240 s) talks about this as follows: “The unusual glow of minerals is caused by cathode, ultraviolet, and x-rays. In the world of dead stone, those minerals light up and shine most brightly, which, having fallen into the zone of ultraviolet light, tell about the smallest impurities of uranium or manganese included in the composition of the rock. Many other minerals that do not contain any impurities also flash with a strange "unearthly" color. I spent the whole day in the laboratory, where I observed the luminescent glow of minerals. Ordinary colorless calcite colored miraculously under the influence of various light sources. Cathode rays made the crystal ruby red, in ultraviolet it lit up crimson red tones. Two minerals - fluorite and zircon - did not differ in x-rays. Both were green. But as soon as the cathode light was turned on, the fluorite turned purple, and the zircon turned lemon yellow.” (p. 11).
Qualitative chromatographic analysis
Chromatograms obtained by TLC are often viewed in ultraviolet light, which makes it possible to identify a number of organic substances by the color of the luminescence and the retention index.
Catching insects
Ultraviolet radiation is often used when catching insects in the light (often in combination with lamps emitting in the visible part of the spectrum). This is due to the fact that in most insects the visible range is shifted, compared to human vision, to the short-wavelength part of the spectrum: insects do not see what a person perceives as red, but they see soft ultraviolet light. Perhaps that is why when welding in argon (with an open arc), flies are fried (they fly into the light and there the temperature is 7000 degrees)!
With the discovery of infrared radiation, the well-known German physicist Johann Wilhelm Ritter had a desire to study opposite side of this phenomenon.
After some time, he managed to find out that at the other end it has considerable chemical activity.
This spectrum became known as ultraviolet rays. What it is and what effect it has on living terrestrial organisms, let's try to figure it out further.
Both radiations are in any case electromagnetic waves. Both infrared and ultraviolet, they limit the spectrum of light perceived by the human eye on both sides.
The main difference between these two phenomena is the wavelength. Ultraviolet has a fairly wide wavelength range - from 10 to 380 microns and is located between visible light and X-rays.
Differences between infrared and ultraviolet IR radiation has the main property - to radiate heat, while ultraviolet has a chemical activity, which has a tangible effect on the human body.
How does ultraviolet radiation affect humans?
Due to the fact that UV is divided by the difference in wavelength, they biologically affect the human body in different ways, so scientists distinguish three sections of the ultraviolet range: UV-A, UV-B, UV-C: near, middle and far ultraviolet.
The atmosphere that envelops our planet acts as a protective shield that protects it from the Sun's ultraviolet flux. Far radiation is retained and absorbed almost completely by oxygen, water vapor, carbon dioxide. Thus, insignificant radiation enters the surface in the form of near and medium radiation.
The most dangerous is radiation with a short wavelength. If short-wave radiation falls on living tissues, it provokes an instant destructive effect. But due to the fact that our planet has an ozone shield, we are safe from the effects of such rays.
IMPORTANT! Despite natural protection, we use some inventions in everyday life that are sources of this particular range of rays. This welders and ultraviolet lamps, which, unfortunately, cannot be abandoned.
Biologically, ultraviolet affects human skin as a slight redness, sunburn, which is a fairly mild reaction. But it is worth considering the individual feature of the skin, which can specifically respond to UV radiation.
Exposure to UV rays also adversely affects the eyes. Many are aware that ultraviolet affects the human body in one way or another, but not everyone knows the details, so we will try to understand this topic in more detail.
UV mutagenesis or how UV affects human skin
It is impossible to completely refuse the sun's rays on the skin, this leads to extremely unpleasant consequences.
But it is also contraindicated to go to extremes and try to acquire an attractive shade of the body, exhausting yourself under the merciless rays of the sun. What can happen in case of uncontrolled stay under the scorching sun?
If redness of the skin is found, this is not a sign that after a while, it will pass and a nice, chocolate tan will remain. The skin is darker due to the fact that the body produces a coloring pigment, melanin, which fights against the adverse effects of UV on our body.
Moreover, redness on the skin does not remain long, but it can lose elasticity forever. Epithelial cells may also begin to grow, visually reflected in the form of freckles and age spots, which will also remain for a long time, or even forever.
Penetrating deep into tissues, ultraviolet light can lead to ultraviolet mutagenesis, which is damage to cells at the gene level. The most dangerous can be melanoma, in case of metastasis of which death can occur.
How to protect yourself from ultraviolet radiation?
Is it possible to protect the skin from the negative effects of ultraviolet radiation? Yes, if, while on the beach, you follow just a few rules:
- It is necessary to be under the scorching sun for a short time and at strictly defined hours, when the acquired light tan acts as photoprotection of the skin.
- Be sure to use sunscreen. Before you buy this kind of product, be sure to check if it can protect you from UV-A and UV-B.
- It is worth including in the diet foods that contain the maximum amount of vitamins C and E, as well as rich in antioxidants.
If you are not on the beach, but are forced to be in the open air, you should choose special clothes that can protect your skin from UV.
Electrophthalmia - the negative effect of UV radiation on the eyes
Electrophthalmia is a phenomenon that occurs as a result of the negative effects of ultraviolet radiation on the structure of the eye. UV waves with medium ranges in this case are very damaging to human vision.
Electrophthalmia These events most often occur when:
- A person observes the sun, its location, without protecting the eyes with special devices;
- Bright sun in open space (beach);
- The person is in a snowy area, in the mountains;
- Quartz lamps are placed in the room where the person is located.
Electrophthalmia can lead to corneal burns, the main symptoms of which are:
- Tearing of the eyes;
- Significant pain;
- Fear of bright light;
- Redness of the protein;
- Edema of the epithelium of the cornea and eyelids.
About statistics, the deep layers of the cornea do not have time to be damaged, therefore, when the epithelium heals, vision is fully restored.
How to provide first aid for electrophthalmia?
If a person is faced with the above symptoms, it is not only aesthetically unpleasant, but can also cause unimaginable suffering.
First aid is pretty simple:
- First rinse eyes with clean water;
- Then apply moisturizing drops;
- Put on glasses;
To get rid of pain in the eyes, it is enough to make a compress from wet black tea bags, or grate raw potatoes. If these methods do not help, you should immediately seek help from a specialist.
To avoid such situations, it is enough to purchase social sunglasses. The UV-400 marking indicates that this accessory is able to protect the eyes from all UV radiation.
How is UV radiation used in medical practice?
In medicine, there is the concept of "ultraviolet starvation", which can occur in case of prolonged avoidance of sunlight. In this case, unpleasant pathologies may arise, which can be easily avoided using artificial sources of ultraviolet radiation.
Their small impact is able to compensate for the lack of winter vitamin D deficiency.
In addition, such therapy is applicable in case of joint problems, skin diseases and allergic reactions.
With UV radiation, you can:
- Increase hemoglobin, but lower sugar levels;
- Normalize the work of the thyroid gland;
- Improve and eliminate problems of the respiratory and endocrine system;
- With the help of installations with ultraviolet radiation, rooms and surgical instruments are disinfected;
- UV rays have bactericidal properties, which is especially useful for patients with purulent wounds.
IMPORTANT! Always, using such radiation in practice, it is worth familiarizing yourself not only with the positive, but also with the negative aspects of their impact. It is strictly forbidden to use artificial, as well as natural UV radiation as a treatment for oncology, bleeding, stage 1 and 2 hypertension, and active tuberculosis.
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 light that is captured by the eye of humans and animals (400-750 nm);
- warm oxidizing (over 750 nm).
Each part finds its use and has 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.
History of the discovery of UV radiation
The first mentions date back to the 13th century in the descriptions of a philosopher from India. He wrote about the invisible violet light that he discovered. However, the technical capabilities of that time were clearly not enough to confirm this experimentally and study it in detail.
It was possible five centuries later, a physicist from Germany, Ritter. It was he who conducted experiments on silver chloride on its decay under the influence of electromagnetic radiation. The scientist saw that the given the process is underway not in the region of light that had already been discovered 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 subsequently underwent a thorough analysis and study by various scientists. A great contribution to this was made by such people as: Alexander Becquerel, Warsawer, Danzig, Macedonio Melloni, Frank, Parfenov, Galanin and others.
general characteristics
What is the application of which today is so widespread in various branches of human activity? First, it should be noted that this light appears only at very high temperatures from 1500 to 2000 0 C. It is in this range that UV reaches its peak activity in terms of exposure.
By physical nature, this is an electromagnetic wave, the length of which varies over a fairly wide range - from 10 (sometimes from 2) to 400 nm. The entire range of this radiation is conditionally divided into two areas:
- near spectrum. It reaches the Earth through the atmosphere and the ozone layer from the Sun. Wavelength - 380-200 nm.
- Far (vacuum). It is actively absorbed by ozone, air oxygen, atmospheric components. It is possible to explore only with special vacuum devices, for which it got its name. Wavelength - 200-2 nm.
There is a classification of species that have ultraviolet radiation. Properties and application finds each of them.
- Near.
- Further.
- Extreme.
- Average.
- Vacuum.
- Long wavelength black light (UV-A).
- Shortwave germicidal (UV-C).
- Medium wave UV-B.
Each species has its own wavelength of ultraviolet radiation, but they are all within the general limits already indicated earlier.
UV-A, or the so-called black light, is interesting. The fact is that this spectrum has a wavelength of 400-315 nm. This is on the border with visible light, which the human eye is able to capture. Therefore, such radiation, passing through certain objects or tissues, is able to move into the region of visible violet light, and people distinguish it as black, dark blue or dark purple.
The spectra produced by ultraviolet radiation sources can be of three types:
- ruled;
- continuous;
- molecular (band).
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, man-made;
- laser.
The first group includes the only type of concentrator and emitter - the Sun. It is the celestial body that gives the most powerful charge of this type of waves, which are able to pass through and reach the surface of the Earth. However, not in its entirety. Scientists put forward the theory that life on Earth originated only when the ozone screen began to protect it from excessive penetration of harmful UV radiation in high concentrations.
It was during this period that protein molecules, nucleic acids and ATP became able to exist. Until today, the ozone layer enters into close interaction with the bulk of UV-A, UV-B and UV-C, neutralizing them and preventing them from passing through. Therefore, protection from ultraviolet radiation of the entire planet is exclusively his merit.
What determines the concentration of ultraviolet radiation penetrating the Earth? There are several main factors:
- ozone holes;
- height above sea level;
- solstice height;
- atmospheric dispersion;
- the degree of reflection of rays from earth's natural surfaces;
- cloud vapor state.
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 use of which can be extremely useful in various fields of activity. Artificial sources include:
- Erythema lamps that have the ability to activate the synthesis of vitamin D in the skin. This prevents and cures rickets.
- Devices for solariums, in which people get not only a beautiful natural tan, but are also treated for diseases that occur when there is a lack of open sunlight (the so-called winter depression).
- Attractant lamps that allow you to fight insects indoors safely for humans.
- Mercury-quartz devices.
- Excilamp.
- Luminous devices.
- Xenon lamps.
- gas discharge devices.
- High temperature plasma.
- Synchrotron radiation in accelerators.
Another type of source is lasers. Their work is based on generating various gases- both inert and not. Sources can be:
- nitrogen;
- argon;
- neon;
- xenon;
- organic scintillators;
- crystals.
More recently, about 4 years ago, a free electron laser was invented. The length of ultraviolet radiation in it is equal to that observed in vacuum conditions. UV laser suppliers are used in biotechnology, microbiological research, 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 deficiency, diseases can occur. This became clear only at the beginning of the last century. Artificial irradiation with special UV-A in the required norms is capable of:
- activate the immune system;
- cause the formation of important vasodilating compounds (histamine, for example);
- strengthen the musculoskeletal system;
- improve lung function, increase the intensity of gas exchange;
- 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 develop 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;
- regenerating;
- painkiller.
These properties largely explain wide application UV in medical institutions of any type.
However, in addition to the above advantages, there are also negative aspects. There are a number of diseases and ailments that can be acquired if you do not get enough or, on the contrary, take the considered waves in excess.
- Skin cancer. This is the most dangerous exposure to ultraviolet radiation. Melanoma can form with excessive influence of waves from any source - both natural and man-made. This is especially true for lovers of tanning in the solarium. In everything, measure and caution are necessary.
- Destructive effect on the retina of the eyeballs. In other words, a cataract, pterygium, or sheath burn may develop. The harmful excessive effects of UV on the eyes have been proven by scientists for a long time and confirmed by experimental data. Therefore, when working with such sources, you should observe. On the street, you can protect yourself with the help of dark glasses. However, in this case, you should be wary of fakes, because if the glasses are not equipped with UV-repellent filters, then the destructive effect will be even stronger.
- Burns on the skin. IN summer time they can be earned by uncontrollably exposing yourself to UV for long periods of time. In winter, you can get them because of the peculiarity of the snow to reflect these waves almost completely. Therefore, irradiation occurs both from the side of the Sun and from the side of snow.
- Aging. If people are exposed to UV for a long time, then they begin to show signs of skin aging very early: lethargy, wrinkles, sagging. This is due to the fact that the protective barrier functions of the integument are weakened and violated.
- Impact with consequences over time. They consist in manifestations of negative influences not in young age but closer to old age.
All of these results are consequences of misdosing UV, ie. they occur 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 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 effect on organisms;
- the ability to cause the glow of various substances in different shades visible to the human eye (luminescence).
This allows wide use of ultraviolet radiation. Application is possible in:
- spectrometric analyses;
- 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 certain type UV with its own spectrum and wavelength. Recently, this type of radiation has been actively used in physical and chemical research (determination of the electronic configuration of atoms, the crystal structure of molecules and various compounds, work with ions, analysis of physical transformations on various space objects).
There is another feature of the effect of UV on substances. Some polymeric materials are capable of decomposing under the influence of intense permanent source wave data. For example, such as:
- polyethylene of any pressure;
- polypropylene;
- polymethyl methacrylate or organic glass.
What is the impact? Products made from these materials lose color, crack, fade, and eventually collapse. Therefore, they are called sensitive polymers. This feature of carbon chain degradation under solar illumination conditions is actively used in nanotechnologies, X-ray lithography, transplantology, and other fields. This is done mainly to smooth out the surface roughness of the products.
Spectrometry is a major field 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, 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 humans. Therefore, animals fly to the source, where they are destroyed.
Use in solariums - special installations of vertical and horizontal type, in which the human body is exposed to UV-A. This is done to activate the production of melanin in the skin, giving 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 protecting the eyes and 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 summarized in several points:
- All types of inflammatory processes, open wounds, suppuration and open seams.
- With injuries of tissues, bones.
- For burns, frostbite and skin diseases.
- With respiratory ailments, tuberculosis, bronchial asthma.
- With the emergence and development of various types of infectious diseases.
- With ailments accompanied by severe pain, neuralgia.
- Diseases of the throat and nasal cavity.
- Rickets and trophic
- Dental diseases.
- Regulation of blood pressure, normalization of the heart.
- The development of cancerous tumors.
- 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 human lives, preserving and restoring their health.
Another option for using UV from a medical and biological point of view is the disinfection of premises, 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 are killed.
The main problem when using such radiation for sterilization and disinfection of a room is the area of illumination. After all, organisms are destroyed only with the direct impact of direct waves. Everything that remains outside continues to exist.
Analytical work with minerals
The ability to induce luminescence in substances makes it possible to use UV to analyze the qualitative composition of minerals and valuable rocks. In this regard, precious, semi-precious and ornamental stones are very interesting. What kind of shades they do not give when irradiated with cathode waves! Malakhov, the famous geologist, wrote about this very interestingly. His work tells about observations of the glow of the color palette, which minerals can give in different sources of radiation.
So, for example, topaz, which has a beautiful saturated blue color in the visible spectrum, glows bright green when irradiated, and emerald - red. Pearls can't give any at all specific color and shimmers with many colors. The resulting spectacle is simply fantastic.
If the composition of the studied rock contains uranium impurities, then the highlight will show a green color. Melite impurities give a blue, and morganite - a lilac or pale purple hue.
Use in filters
For use in filters, ultraviolet germicidal radiation is also used. The types of such structures can be different:
- hard;
- gaseous;
- liquid.
Such devices are mainly used 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 identify it by belonging to a particular class of organic compounds.
Drinking water treatment
Disinfection by ultraviolet radiation of drinking water is one of the most modern and high-quality methods of its purification from biological impurities. The advantages of this method are:
- reliability;
- efficiency;
- the absence of foreign products in the water;
- safety;
- profitability;
- preservation of the organoleptic properties of water.
That is why today this method of disinfection keeps pace with traditional chlorination. The action is based on the same features - the destruction of the DNA of harmful living organisms in the composition of water. Use UV with a wavelength of about 260 nm.
In addition to direct impact on pests, ultraviolet light is also used to destroy the remains 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 action 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 finds application UV. Each artist used white, containing different heavy metals in each epochal period of time. Thanks to irradiation, it is possible to obtain so-called underpaintings, which provide information about the authenticity of the painting, as well as about the specific technique, manner of painting of each artist.
In addition, the lacquer film on the surface of products belongs to sensitive polymers. Therefore, it is capable of aging under the influence of light. This allows you to determine the age of compositions and masterpieces of the artistic world.
Light therapy (phototherapy)- Light treatment. Infrared radiation. visible radiation. Ultraviolet radiation
Phototherapy is a dosed effect of infrared, visible and ultraviolet radiation on the human body for the purpose of treatment. For this, special phototherapy lamps are used. This method of treatment is also often called phototherapy (from the Greek photos - light).
Since ancient times, people have paid attention to the healing effects of sunlight on human health. The solar spectrum consists of 10% ultraviolet rays, 40% visible rays and 50% infrared rays. All these types of electromagnetic radiation are widely used in medicine.
In medical institutions for this type of treatment, artificial emitters with incandescent filaments are used. They are heated by electric current.
Infrared radiation: impact on humans, treatment
Infrared radiation is thermal radiation. Its rays are able to penetrate into the tissues of the body to a greater depth, compared to other types of light energy. This leads to heating of the entire thickness of the skin and part of the subcutaneous tissues. Deeper structures are not affected by this type of radiation.
The main indications for its use are: some diseases of the musculoskeletal system, non-purulent chronic and subacute inflammatory local processes occurring, including in the internal organs. It is used to treat patients with diseases of the central and peripheral nervous system, peripheral vessels, eyes, ear, and skin. This method also helps with residual effects after burns and frostbite.
This type of radiation contributes to the elimination of inflammatory processes, accelerates healing, increases local resistance and anti-infective protection.
If the rules for the procedure are violated, there is a danger of serious overheating of tissues and the formation of thermal burns. There may also be an overload of blood circulation, which is contraindicated in cardiovascular diseases.
Contraindications for use are: the presence of benign or malignant neoplasms, active forms of tuberculosis, stage III hypertension, bleeding, and circulatory failure.
Visible radiation
Visible radiation is a section of the general electromagnetic spectrum, which consists of 7 colors: red, orange, yellow, green, blue, indigo, violet. It can penetrate the skin to a depth of 1 cm. But it has the main effect through the retina.
A person's perception of the color components of visible light affects his central nervous system. This type of radiation is used in the treatment of patients with various diseases nervous system.
As you know, for example, yellow, green and orange colors enhance mood, while blue and purple act the other way around. Red stimulates the activity of the cerebral cortex. Blue - inhibits neuropsychic activity. White color is very important for the emotional state of a person. Its lack leads to depression.
Ultraviolet radiation
Ultraviolet radiation has the most powerful energy and activity. However, at the same time, its rays are able to penetrate human tissues only to a depth of 1 mm.
Our skin and mucous membranes are most sensitive to this type of rays. Young children are more sensitive to ultraviolet light.
Ultraviolet irradiation enhances body's defenses, has a desensitizing effect, improves fat metabolism. It also normalizes the processes of blood coagulation, improves the functions of external respiration, increases the activity of the adrenal cortex. Deficiency of ultraviolet leads to beriberi, reduced immunity, deterioration of the nervous system and manifestations of mental instability.
Indications for the use of ultraviolet radiation
Indications for use are diseases of the skin, joints, respiratory organs, female genital organs, peripheral nervous system. It is prescribed for the speedy healing of wounds and in order to compensate for ultraviolet deficiency in the body. Prevents rickets.
Contraindications to the use of ultraviolet radiation
Contraindications are: acute inflammatory processes, tumors, bleeding, stage III hypertension, stage II-III circulatory failure, active forms of tuberculosis, etc.
laser radiation.
Laser or quantum therapy is a method of phototherapy, which consists in the use of beams of laser radiation. Laser radiation has the following therapeutic properties: anti-inflammatory, reparative, hypoalgesic, immunostimulating and bactericidal.
It is prescribed for a large number of diseases of the musculoskeletal, cardiovascular, respiratory, digestive, nervous, genitourinary systems. It is also used for the treatment of skin diseases, diseases of the upper respiratory tract and diabetic angiopathy. Contraindications are the same as for other types of light radiation.
