The Franck-Hertz experiment provided clear proof of the ideas of Neils Bohr as regards electrons orbiting atomic nuclei and doing so at clearly defined energy levels (which translates into orbitals). By extension, conducting this experiment on different materials allows the energy levels of the electrons in a material to be discovered. Materials might be identified in this way. A sample could be experimented on and the energy level of the material discovered and compared to know materials, thus revealing its identity.