= Laue X-ray diffraction experiment of 1912
{c}
<Max von Laue> proposed crystal <X-ray diffraction> and wrote the theoretical section; <Walther Friedrich> and <Paul Knipping> performed the experiments.<Interferenz-Erscheinungen bei Röntgenstrahlen by Walther Friedrich, Paul Knipping and Max von Laue>[pp. 303–304, 311: section authorship]{ref}
An <X-ray tube>, lead apertures and shielding supplied a narrow beam through a crystal on a <goniometer>. <Photographic plates> recorded the direct beam and separate spots. <Copper(II) sulfate> trials preceded oriented <zinc blende>. Optical alignment was checked with <X-rays>. Removing the crystal removed the extra spots; grinding destroyed their ordered arrangement; translation preserved it, while tilt changed it. Rotation about the beam rotated the pattern.<Interferenz-Erscheinungen bei Röntgenstrahlen by Walther Friedrich, Paul Knipping and Max von Laue>[pp. 311–318: apparatus and controls]{ref}
Spots and orientation dependence supported <wave interference> and three-dimensional crystal periodicity. They determined neither all atomic positions nor an absolute <wavelength> scale. The authors left open whether the selected radiation originated as crystal <fluorescence> or was already in the incident beam. This differs from the modern <Laue method>.<Interferenz-Erscheinungen bei Röntgenstrahlen by Walther Friedrich, Paul Knipping and Max von Laue>[pp. 310–311, 320–322: inference and spectral uncertainty]{ref}
The 1914 <Nobel Prize in Physics> went to <Max von Laue>; the discovery's experimental account remains jointly credited to <Walther Friedrich> and <Paul Knipping>.<The Nobel Prize in Physics 1914 by Nobel Prize Outreach>[1914 award and laureate]{ref} The subsequent inference of particular <crystal structures> is developed under <X-ray crystallography>.
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