Electron diffraction from thin films of solidified gases

Electron diffraction studies have been carried out on thin films of the solidified gases argon, krypton, neon, xenon, oxygen and nitrogen, using a liquid helium cooled specimen stage. In transmission all the inert gases studied were found to crystallize in their normal close-packed cubic structures. When deposited on a (111) single-crystal silver face and studied in reflection, solid argon, neon and xenon were observed again to crystallize with close-packed cubic structures. Solid krypton, however, was found to give a pattern consisting of sharp and diffuse arcs which are found to be consistent with the formation, during deposition, of stacking faults in (111) krypton planes. The probability of plane faulting α was deduced to lie in the range 2√3 - 3 < α < ½, indicating that for krypton under the conditions of the experiment the close-packed hexagonal structure is almost as likely as the close-packed cubic structure. Electron diffraction studies on solid α nitrogen confirmed the recent results of Hörl and Marton. The diffraction patterns obtained from solid β oxygen were in agreement with the R m space group proposed by Hörl. The 10.4 ring, not observed by Hörl but allowed by his proposed structure, was present in all the diffraction patterns obtained.