Powder diffraction is the most common method of XRD. The analysis involves grinding the substance under analysis into a finely ground and homogenized powder and a cathode ray tube generates a concentrated X-ray directed toward the sample. The collision of the beam and sample produces diffracted X-rays that reveal the substance's crystal structures and atomic spacing. A Phillips XPERT MPD diffractometer often records this data.
Thin film diffraction is a collection of XRD techniques used for analyzing a film grown on a substrate. Typical X-rays do not work on film samples because they penetrate both the film and the substrate. As a result, the substrate's properties may be confused with those of the film. On the other hand, thin film diffraction analysis allows precise measurements of a film's density, roughness and texture.
SAXS instruments analyze the scattering angles of beams that result from an X-ray colliding with a sample. The scattering angles often differ from the original beam by less than 1 degree so a lab must use large samples and high-quality optical gear to obtain an accurate sample. For instance, the University of California at Santa Barbara has a 3.5-meter-long SAXS instrument for analyzing biological macromolecules and nano-porous materials.
Scientists often employ X-ray crystallography in the field of biochemistry to analyze protein and DNA samples. This method employs a high-intensity X-ray device that measures the crystalline structure of the specimen multiple times. The series of measurements is averaged to reduce the impact of a statistical aberration. A common disadvantage of this type of XRD is the difficulty of measuring the phase of the substance. That is, the crystallography of substances may not remain in a single state but cycle through phases. XRD only can take snapshots of a sample rather than evaluate changes over an entire cycle.