Abstract

The electron-beam-excited NVV Auger electron spectrum of HI is presented together with a new recording of the X-ray excited photoelectron spectrum of the I4d core lines. It is shown that the initial I4d core hole state is vibrationally excited. The NVV Auger electron spectrum is dominated by transitions lo the ?^-2 dicationic states of ³?^–, ¹? and ¹?⁺ symmetry. Vibrational structure is resolved in all Auger transitions and the equilibrium geometry of both the initial core-hole state and the final dicationic states have been determined. A splitting of the ³?₁^– and ³?₀^– states of the 220 meV is observed. The dissociation of the ?^-2 dicationic states in terms of Coulomb explosion is discusses and tentative potential curves are given.