The first X-ray experiment was performed by Max von Laue in Munich in 1912. X-rays had been discovered 17 years earlier by Roentgen but there was, at the time of von Laue's work, no agreement on exactly what X-rays were. There was some experimental evidence that X-rays were high energy particles (like electrons); other data indicated that X-rays might be waves. Von Laue surmised that, if X-rays were waves, they would have rather short wavelengths (on the order of 1 x 10-10 m) and the dimensions of the objects in crystals would be the appropriate size to produce the phenomenon of diffraction. He exposed a crystal of copper sulfate to X-rays and recorded the diffraction pattern on a piece of photographic film:

This experiment proved the wave nature of X-rays and began the exploration of molecular structure by X-ray diffraction methods.