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
Absorbed dose of absorbed dose in tissue is of fundamental importance in radiobiology as it is the measure of the amount of energy the incident radiation is imparting to the target tissue. The absorbed dose is equal to the radiation exposure (ions or C/kg) of the radiation beam multiplied by the ionization energy of the medium to be ionized. For example, the ionization energy of dry air at 20 °C and 101.325 kPa of pressure is . (33.97 eV per ion pair) Therefore, an exposure of (1 roentgen) would deposit an absorbed dose of (0.00876 Gy or 0.876 rad) in dry air