is a method to determine the atomic and molecular structure of a crystal
solid crystals of purified protein are placed in an X-ray beam, and the pattern of deflected X rays is used to predict the positions of the thousands of atoms within the protein crystal
an ordinary microscope can’t capture the structure of a molecule. This is because the wavelength of visible light is much bigger than atoms.
X-rays with a wavelength between 10−8 to 10−12 meters are about the same size as atoms (i.e. atoms have an average radius of about 10−10 meters)
there are no lenses to diffract x-rays, thus x-rays shot at a crystal containing the molecules are diffracted out onto a detector, and math is used to work back the original shape/structure of the molecule