• Ion interference:
  Up to now no interference has been observed with ions. The main difficulty is the low intensity of the source. Ultimately ionisation from only one atom of the tip constitutes the source. The intensity reduces to a few counts per second as the magnification is increased. This requires measurements over time periods of about 20 minutes to obtain a visible interference pattern. However, at the moment the stability of the tip is not sufficient for such long measurement times.
• Electron interference:
  Because the intensity of the beam is some orders of magnitude higher for electrons than for ions, it is no problem to observe interference of electrons for a broad range of energies (from about 300 eV upwards). The interference pattern shown on the picture was measured with 400 eV electrons. It is a single frame recorded by our video camera. The spacing of the interference maxima is about 0.5 mm. As one can see the interference pattern is formed by thousands of bright pixles, each one caused by a single electron. In such a way the fascinating duality of wave (interference) and particle (bright pixel caused by a single electron) is clearly expressed.
  Interfernce pattern for low-energy electrons (400 eV). (JPG, 8k)

Back to top of page