Vibrationally Enhanced Dissociation of Diatomic Molecules.

The impact parameter method for electron impact excitation of diatomic molecules has been extended to treat dissociation and to include the effects of vibrational and rotational excitation. The method was found to agree well with previous theoretical calculations of excitation and dissociation cross sections for H2. The agreement with experimental cross sections is poorer but consistant with our understanding of the processes. The method has been applied to electron impact excitation and dissociation of 02, S2, HCl, and HgBr through optically allowed transitions. Vibrational excitation of the molecule can significantly affect the cross sections for these processes, either increasing or decreasing the cross sections by as much as 2 orders of magnitude, whereas, rotational excitation has a much smaller effect on the cross sections.