Sterilizing viruses sets UV LED light in the sanitizing Spotlight.


Sterilizing viruses set UV LED light in the sanitizing Spotlight.

The so-called Covid-19 virus pandemic has breathed new life into many decades-old techniques that able to kill viruses & bacteria at a 99.999 % rate.

UV radiation was discovered in 1801 when the German physicist Johann Wilhelm Ritter observed that invisible rays just beyond the violet end of the visible spectrum darkened silver chloride-soaked paper more quickly than violet light itself. He called them "(de-)oxidizing rays" (German: de-oxidierende Strahlen) to emphasize chemical reactivity and to distinguish them from "heat rays", discovered the previous year at the other end of the visible spectrum. The simpler term "chemical rays" was adopted soon afterwards, and remained popular throughout the 19th century, although some said that this radiation was entirely different from light (notably John William Draper, who named them "tithonic rays"[10][11]). The terms "chemical rays" and "heat rays" were eventually dropped in favor of ultraviolet and infrared radiation, respectively.[12][13] In 1878 the sterilizing effect of short-wavelength light by killing bacteria was discovered. By 1903 it was known the most effective wavelengths were around 250 nm. In 1960, the effect of ultraviolet radiation on DNA was established.[14]

The discovery of the ultraviolet radiation with wavelengths below 200 nm, named "vacuum ultraviolet" because it is strongly absorbed by the oxygen in air, was made in 1893 by the German physicist Victor Schumann.[15] 

This section of Article referred to Wikipedia site.