They took a crystal, this is a single crystal of nickel that has regular planes of atoms, and those planes are spaced on the order of an angstrom or less apart, and they irradiated this with x-rays.

他们取了个晶体,一个具有规则原子平面的，镍晶体,这些面间距差不多也是一埃或者更少，它们放射出X射线。

麻省理工公开课 - 固态化学导论课程节选