Direct methods for analyzing these specimens are classified based on if they measure real-space. Hermann–Mauguin notation was developed to describe these specimens. (15[1])An electron gun is fired at one of these specimens in ultra-high vacuum, after which filtered electrons (-5[1])are measured on a hemispherical fluorescent screen in LEED. The Debye-Scherrer method allows analysis of imperfect examples of these specimens (15[1])due to being able to grind the sample to a (*) powder. When refining data from these specimens, one must identify the shape of their unit cells (10[1])and subsequently their space groups. Bragg’s law (10[2])describes (10[1])diffraction (10[1])through, for 10 points, (10[2])what solids with repeating structures? (10[1])■END■ (10[2])