Resonant LII,III x-ray Raman scattering from HCl

We have studied the spectral features of Cl LII,III resonant x-ray Raman scattering of HCl molecules in gas phase both experimentally and theoretically. The theory, formulated in the intermediate-coupling scheme, takes into account the spin-orbital and molecular-field splittings in the Cl 2p shells, as well as the Coulomb interaction of the core hole with unoccupied molecular orbitals. Experiment and theory display nondispersive dissociative peaks formed by decay transitions in both molecular and dissociative regions. The molecular and atomic peaks collapse in a single narrow resonance because the dissociative potentials of core-excited and final states are parallel to each other along the whole pathway of the nuclear wave packet.