Portable three-dimensional imaging for an explicit identification of the internal state of diatomic molecular ions

A transportable experimental set-up was developed at the Universit\'{e} catholique de Louvain in Louvain-la-Neuve, Belgium to measure the internal energies of small diatomic molecular ions such as H$_{2}^{+}$. The technique, which scheme was first developed by D. P. de Bruijn and J. Los (Rev. Sci. Intstrum. 53, 1020, 1982) and included a resonant dissociative charge exchange with alkali atoms, consists in measuring the positions of the fragments and their flight time difference with two position sensitive detectors. The measured kinetic energy release is directly related to the original level of vibrational excitation of H$_{2}^{+}$. Details and applications will be presented.