Waves as particles

Demonstrated that X rays scattered by matter have increased wavelengths, known as the Compton effect. This was a clear demonstration of the particle aspects of an energetic wave, and Compton began referring to this aspect as photons.
 Arthur Holly Compton United States 1923 Waves as particles

Demonstrated that X rays scattered by matter have increased wavelengths, known as the Compton effect. This was a clear demonstration of the particle aspects of an energetic wave, and Compton began referring to this aspect as photons.