The effects of electron exchange and spin orbit interaction in dissociative excitation processes in ${\mathrm{H}}_2$ molecules have been explored using excitation by polarized electrons. Observations of the circular and linear Stokes polarizations of the Balmer-alpha photons determined the alignment and orientation of the excited atomic hydrogen atoms, the excited molecular states, and the dissociative excitation processes via predissociation with short and long range transitions.

• Received 4 November 2003

DOI:https://doi.org/10.1103/PhysRevLett.93.073201