Photo from the Nobel Foundation archive.
Arthur Holly Compton
Born: 10 September 1892, Wooster, OH, USA
Died: 15 March 1962, Berkeley, CA, USA
Affiliation at the time of the award: University of Chicago, Chicago, IL, USA
Prize motivation: "for his discovery of the effect named after him."
Prize share: 1/2
According to Albert Einstein's photoelectric effect theory, light consists of quanta, "packages" with definite energies corresponding to certain frequencies. A light quantum is called a photon. When Arthur Compton directed X-ray photons onto a metal surface in 1922, electrons were emancipated and the X-rays' wavelength increased because some of the incident photon energy was transferred to the electrons. The experiment confirmed that electromagnetic radiation could also be described as photon particles following the laws of mechanics.
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