By measuring the momentum vectors of all heavy fragment of a molecule in coincidence with one or more
photoelectron or Auger electron COLTRIMS allows to study the ionization process in the molecular frame of
reference. The fragmentation process of the remaining molecular ion is often rapid enough, that the molecule has
no time to rotate before fragmentation. Then the molecular orientation can be inferred from the fragment direction
for each ionization event.
We have used this technique to study double photo ionization of D2 and of K-shell ionization of several small
molecules (CO, N2, C2H2, C2H4, C2H6).
The experiments are performed by the COLTRIMS collaboration @ ALS.