Spectroscopic techniques for studying bandstructure

The existence of bands and a map of their desities of states can be shown using either photoelectron spectroscopy or x-ray analysis.

Photoelectron spectroscopy can be used here in much the same way as when dealing with discrete molecules. The densities of states of discrete molecules are made up of a set of widely separated, narrow peaks, corresponding to energies of discrete molecular orbitals. When looking at the photoelectron spectrum the peaks exist as photoelectrons with discrete ionisation energies.

Equivalent information about solids can be obtained from X-ray emission bands. Electrons are ejected (by electron bombardment) from the inner closed shells of the atoms. As electrons from the valence band fall into the vacancies created x-rays are emitted. (fig. 6)