The spectroscopy of the hydrogen molecule near its ionization limit

The absorption and ionization cross sections of molecular hydrogen for the wavelength region from 850 to 792 A are given. This region contains the dissociation and ionization limit as well. The rotational structure of the bands could partially be resolved in this experiment. As the dissociation of the molecule results in an excited hydrogen atom, this process can be followed by measuring the atomic fluorescence. Part of the excited atoms is found to be in the metastable 2 doublet S-state. From fluorescence as well as absorption and ionization measurements it can be shown, that even above the ionization limit the absorption due to the D-state of the molecule leads to dissociation. The experimental results seem to point out, that the spectroscopic value of the ionization limit has to be shifted to lower energies.