The use of ultra-violet rays. "Black light" in science and industry

The history of the "black light" and its application in various fields of science and industry.

In 1851, Ritter had discovered rays of violet end of the spectrum, the existence of which no one knew. Discovered rays were invisible, but causes severe chemical changes. They proved easily detected using a photographic plate, which darkens the most in the region lying beyond the violet end of the spectrum.

A detailed study of ultraviolet radiation was discovered that it is able to exert a strong physiological effects: kill microorganisms destroy living tissue. In this regard, the use of ultraviolet rays is widely used in medicine and sanitation.

An important feature is the ability to UV rays cause the glow of many substances under their influence. It was very important for the technology, giving an opportunity to explore the composition of different products. But the application of this method is limited by the fact that UV rays have a negative effect on the people who work in areas illuminated with ultraviolet light.

American physicist Robert Wood, working for many years on the study of screens that can separate the visible light from the invisible and receive beams that are actively operating in the fluorescent substance was able to find a screen. They became black glass with nickel oxide. Wood screen placed in front of the quartz lamp will pass only ultraviolet rays having a wavelength of 3650 to 3663 ° A, and visible rays with a wavelength of 3341 A °.

Initially, these rays were called "the light of the Wood", then they were called simply "black light". It was under this name they have entered into a modern science and technology. Feature of rays passed through the glass Wood, is that they, as active agents of fluorescence, no harmful effects on humans and animals.

"Black Light" began to be used in the First World War. The Allies used it for secret alarm. Beyle and Fabre began to use it to deal with the German espionage: illuminating them notes, envelopes and other trinkets could find various drawings, instructions for the bombing and information about the activities of military allies.

After the war, the "black light" quickly found application in industry and science. In the first place it was used in the textile industry, which is of great importance coloring products. For example, artificial silk, the same in daylight, under the influence of "black light" is easily distinguished from each other and from natural silk.

On paper mills on the basis of the color of fluorescence determine the quality of the pulp, as well as its ability to bleaching.

In the chemical industry a "black light" can recognize natural resins and rubber.

Important is the use of "black light" in the study of plant and mineral oils. Oils extracted, for example, in Turkey, Romania and America give different fluorescence.

The use of "black light" in the food industry allows you to fight with a hit on the market spoiled or counterfeit products.

Applications "black light" is very different. But research technique is far from simple. It should be borne in mind that the nature of the fluorescence is affected by many indirect circumstances, such as temperature.

S. Dere for a number of substances to establish full fluorescence spectra with characteristic lines, allowing to make the study more precisely than with a simple color assessment.