Tokyo Tech News

A threshold photoelectron source for the study of cold electron collisions


Published: August 31, 2011

The details of research

The scattering of low-energy electrons by atoms and molecules has been the subject of extensive experimental and theoretical investigations. When the collision energy is very low such as less than 100 meV, the de Broglie wavelength of electrons becomes very much greater than the typical size of an atom or a molecule. Quantum effects dominate the resulting ‘cold electron collisions’.

However, producing an electron beam of such low energy was a formidable task using the conventional technique based on a hot-filament electron source.

Now, Masashi Kitajima and colleagues at Tokyo Institute of Technology, Sophia University and the Institute of Materials Structure Science have developed a new a so-called threshold photoelectron source for producing an ultralow-energy electron beam.

They use a combination of the penetrating field technique and the threshold photoionization of rare-gas atoms using synchrotron radiation as an electron source to produce a high-resolution electron beam at a very low energy.

The total cross section of electron scattering from krypton was successfully obtained with a very high resolution in a wide energy range, including the cold electron collision regime.

The results demonstrate that the threshold photoelectron source is a reliable method for cold electron collision experiments.


  • Authors: Manabu Kurokawa, Masashi Kitajima, Kaiji Toyoshima, Takeshi Odagiri, Hidetoshi Kato, Hirotomo Kawahara, Masamitsu Hoshino, Hiroshi Tanaka, and Kenji Ito
  • Title of original paper: Threshold photoelectron source for the study of low-energy electron scattering: Total cross section for electron scattering from krypton in the energy range from 14 meV to 20 eV.
  • Journal, volume, pages and year: Physical Review A 82, 062707 (2010).
  • Digital Object Identifier (DOI): 10.1103/PhysRevA.82.062707
  • Affiliations: Department of Chemistry, Tokyo Institute of Technology, Department of Physics, Sophia University, Photon Factory, Institute of Materials Structure Science
  • Department website:

The apparatus for cold electron collision experiments employing the threshold photoelectron source.

The apparatus for cold electron collision experiments employing the threshold photoelectron source.

Masashi Kitajima
Graduate School of Science and Engineering Chemistry
Associate Professor