diffraction

Examples of diffraction in the following topics:

• Interference and Diffraction

  • Interference and diffraction are terms that describe a wave interacting with something that changes its amplitude, such as another wave.
  • Diffraction refers to various phenomena that occur when a wave encounters an obstacle.
  • The effects of diffraction are often seen in everyday life.
  • The most striking examples of diffraction are those involving light; for example, the closely spaced tracks on a CD or DVD act as a diffraction grating to form the familiar rainbow pattern seen when looking at a disk.
  • While diffraction occurs whenever propagating waves encounter such changes, its effects are generally most pronounced for waves where the wavelength is roughly similar to the dimensions of the diffracting objects.

• Determining Atomic Structures by X-Ray Crystallography

  • The x-ray beams are diffracted in a characteristic pattern that gives rise to reflections, dark spots on the detector which represent places where constructive interference of the diffracted light has occurred.
  • The crystal is typically rotated with respect to different axes and shot again with X-rays, so that diffraction patterns from all angles of the X-rays hitting the crystal are recorded.
  • X-ray diffraction data have proven useful in identifying the structures of protein parts of viruses, such as HIV, which was instrumental in the design of drugs that can specifically target the virus' needed machinery for its life cycle.
  • An X-ray diffraction pattern of a crystallized protein molecule.
  • When bombarded with x-ray radiation, crystals exhibit a characteristic diffraction pattern.

• The de Broglie Wavelength

  • The angular dependence of the reflected electron intensity was measured and was determined to have the same diffraction pattern as those predicted by Bragg for X-rays.
  • Before the acceptance of the de Broglie hypothesis, diffraction was a property that was thought to only be exhibited by waves.
  • Therefore, the presence of any diffraction effects by matter demonstrated the wave-like nature of matter.
  • Experiments with Fresnel diffraction and specular reflection of neutral atoms confirm the application of the de Broglie hypothesis to atoms, i.e. the existence of atomic waves that undergo diffraction, interference, and allow quantum reflection by the tails of the attractive potential.
  • In 1999, a research team in Vienna demonstrated diffraction for molecules as large as fullerenes.

• Amorphous Solids

  • At an atomic scale, it is difficult to distinguish between the two different types, even using advanced analytical techniques such as x-ray diffraction and transmission electron microscopy.

• Bond Lengths

  • X-ray diffraction of molecular crystals allows for the determination of the three-dimensional structure of molecules and the precise measurement of internuclear distances.

• Chromium

  • As verified by X-ray diffraction, a Cr-Cr quintuple bond (length 183.51(4) pm) has also been described.

• Properties of Waves and Light

  • However, when this single-slit experiment is actually performed, the pattern on the screen is a diffraction pattern in which the light is spread out.

• Crystalline Solids

  • X-ray diffraction data showed the lower melting polymorph to be monoclinic, space group P2.

• The Secondary & Tertiary Structures of DNA

  • Rosalind Franklin, working at King's College, London, obtained X-ray diffraction evidence that suggested a long helical structure of uniform thickness.