Ultraviolet quickly than violet light itself. He called them "oxidizing rays" 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 shortly thereafter, and it remained popular throughout the 19th century, although there were those who held that these were an entirely different sort of radiation from light (notably John William Draper, who named them "tithonic rays"). The terms chemical rays and heat rays were eventually dropped in favor of ultraviolet and infrared radiation, respectively. In 1878 the sterilizing effect of
UV marker emits visible light and make the message readable for human eyes. Fluoresce is caused by a conversion of energy; when the invisible ultraviolet falls on the fluorescent surface, it is absorbed and re-emitted as visible light radiation. The absorption of energy by the electrons in the UV-visible ink enables this to happen. When an extra amount of energy is absorbed, the electrons jump into higher energy orbital patterns surrounding the nucleus. Eventually, the energy is released as visible light when they fall back to their normal orbital shell. The difference between the original electron orbital and the new orbital pattern