But to establish the electromagnetic nature and the undulatory properties of x-rays, many other researchers had to take to the field. Among these were as many as three future Nobel laureates.
Charles Glover Barkla (1877-1944), on studying the double scattering of x-rays by two aligned blocks of carbon, showed that the x-rays scattered at right angles with respect to the direction of propagation of the primary beam, in analogy with what takes place for light and is expected to take place with all electromagnetic waves, they are highly polarized and vibrate perpendicularly to the plane found by the direction of propagation of the primary beam and by that of observation. Barkla received the Nobel Prize for Physics in 1917 "for his discovery of x-radiation characteristic of the elements".
At this point it was known that x-rays were probably of an electromagnetic nature, but their wavelength, which in the 1912 estimates of Wilhelm Wien (1864-1928) and Arnold Sommerfeld (1868-1951), was on the order of a few tenths of an ångström, therefore made it impossible to create a diffraction grating having a step of that order of magnitude.
Max Theodor Felix von Laue (1879-1960) had the genial intuition that a crystal, with its orderly atoms and with a reticular constant on the order of magnitude of an ångström, might represent a natural diffraction grating for x-rays.
He considered the atoms aligned in a crystal as a spatial grating and addressed and solved theoretically the problem of x-ray scattering by that natural grating. His forecasts were experimentally confirmed by W. Friedrich and P. Knipping.
...continues