Charles Glover Barkla
Barkla, Charles Glover (1877-1944), a British physicist, investigated secondary radiation. He demonstrated that X rays are electromagnetic waves and not particles. Barkla won the 1917 Nobel Prize in physics.
Barkla researched the phenomenon of X-ray scattering. When an X-ray beam falls upon a substance, a secondary radiation is emitted. Barkla's research demonstrated that some of the X rays that come back from a material are the original X rays reflected without change, but others (called “characteristic radiation”) are given out by atoms of the material and have different wavelengths from the original radiation. The way in which a solid deflects X rays tells scientists about the size, shape, and arrangement of that solid's molecules. This research laid a foundation for the concept of atomic number. Barkla also showed that secondary radiation of heavy elements has two types of characteristic radiation: a radiation, called K, and a less penetrating radiation, called L .
In 1898, Barkla graduated from University College, Liverpool, with a first-class honors degree in physics and went on to earn a master's degree the following year. He then enrolled at Trinity College, Cambridge, but after 18 months transferred to King's College so that he could sing in its renowned choir. Barkla had a marvelous voice, and his solo concerts were well attended.
In 1902, Barkla was appointed an Oliver Lodge Fellow at Liverpool University, and two years later received his doctorate degree. He stayed in Liverpool until 1909 and became a demonstrator, assistant lecturer, and special lecturer. In 1909, Barkla became professor of physics at King's College, London. He was elected a fellow of the Royal Society in 1912. He held the chair in natural philosophy at the University of Edinburgh in 1913until his death. In his later career, Barkla isolated himself from the scientific community in pursuit of the “J phenomenon,” a type of secondary radiation he felt certain existed but which he never discovered. Increasingly, Barkla cited only his work and rejected generally accepted discoveries and new concepts such as the Compton effect and quantum theory.