Kinetic Energy Distribution ofH(2p)Atoms from Dissociative Excitation ofH2

The kinetic energy distribution of $\mathrm{H}\left(2p\right)$ atoms resulting from electron impact dissociation of ${\mathrm{H}}_2$ has been measured for the first time with uv spectroscopy. A high resolution uv spectrometer was used for the measurement of the H $\mathrm{L}\mathrm{y}\mathrm{m}\mathrm{a}\mathrm{n}-\alpha$ emission line profiles at 20 and 100 eV electron impact energies. Analysis of the deconvolved 100 eV line profile reveals the existence of a narrow line peak and a broad pedestal base. Slow $\mathrm{H}\left(2p\right)$ atoms with peak energy near 80 meV produce the peak profile, which is nearly independent of impact energy. The wings of H $\mathrm{L}\mathrm{y}\mathrm{m}\mathrm{a}\mathrm{n}-\alpha$ arise from dissociative excitation of a series of doubly excited $Q_1$ and $Q_2$ states, which define the core orbitals. The fast atom energy distribution peaks at 4 eV.