Читать книгу Solid State Physics - Philip Hofmann - Страница 20

X‐rays interact rather weakly with matter. A description of X‐ray diffraction can therefore be restricted to single scattering, meaning that we limit our analysis to the case that X‐rays incident upon a crystal sample get scattered not more than once (most are not scattered at all). This is called the kinematic approximation; it greatly simplifies matters and is used throughout the treatment in this book. Furthermore, we will assume that the X‐ray source and detector are placed very far away from the sample so that the incoming and outgoing waves can be treated as plane waves. X‐ray diffraction of crystals was discovered and described by M. von Laue in 1912. Also in 1912, W. L. Bragg came up with an alternative description that is considerably simpler and will serve as a starting point for our analysis.