High-resolution electron-momentum spectroscopy of the valence orbitals of the iodine molecule

Abstract

The valence orbitals of the iodine molecule (I${}_{2}$) have been studied using the high-resolution electron-momentum spectroscopy at impact energies of 1200 and 600 eV. Experimental momentum distributions of outer valence orbitals were compared with the nonrelativistic, scalar relativistic, and spin-orbital relativistic calculations, as well as the relativistic pseudopotential calculation. The experimental cross-section ratios of $8{J}_{g}^{3/2}$ to $17{J}_{g}^{1/2}$, $8{J}_{u}^{3/2}$ to $16{J}_{u}^{1/2}$, and the electron-momentum profiles of orbital $16{J}_{g}^{1/2}$ clearly manifested the relativistic effects. In the inner valence region, the symmetry-adapted-cluster configuration-interaction theory was used to interpret the ionization spectrum and the electron-momentum distributions.