Schorr, S.; Stephan, C.; Törndal, T.; Gunder, R.; Többens, D.M.: X-ray and neutron diffraction of materials for thin film solar cells. In: D. Abou-Ras, T. Kirchartz, U. Rau [Ed.] : Advanced characterization techniques for thin film solar cells. Weinheim: Wiley, 2016. - ISBN 978-3-527-41003-3, p. 421-440

In order to understand natural and artificially produced materials, a detailed understanding of their crystal structures is required. This information is a basis for research in physics, chemistry, biology and materials science. Among the various experimental methods, neutron and X-ray (photon) scattering have become key techniques of choice. Both techniques are complementary. In X-ray scattering, it is almost exclusively the electrons in atoms which contribute to the scattering, whereas neutrons interact with the atomic nuclei. This has an important consequence: the response of neutrons from light atoms (such as hydrogen or oxygen) is much higher than for X-rays, and neutrons easily distinguish atoms of comparable (or even equal) atomic number (see figure 13.1). Due to the fact that neutrons interact with atoms via nuclear rather than electrical forces and nuclear forces are very short-range (of the order of a few Fermis, i.e., 10-15 m), the cross-section for such an interaction is very small. The size of a scattering center (nucleus) is typically 105 times smaller than the distance between the centers. As a consequence, neutrons can travel large distances through most materials without being scattered or absorbed. Thus, neutrons penetrate matter much more deeply than X-rays. While neutron scattering provides insights into the crystal structure with high resolution, X-ray scattering has the advantage that (due to a larger scattering cross-section) measurement durations are usually much shorter, compared with neutron scattering. Additionally, lab-scale X-ray sources are broadly available.