Fig. 3: 2D electron signal maps showing the electron kinetic energy as a function of photon energy, scanned across the cation 1s ionization thresholds, for Na⁺, Mg²⁺, and Al³⁺ ions in water.

The vertical dashed and diagonal dotted lines indicate the 2p⁻² final states (accessed after normal AM decay) and dispersive 2p⁻²3p and 2p⁻²3s final states (e.g., accessed after spectator AM decay), respectively. For Al³⁺, the dispersive feature starting from about 1575 eV photon energy is due to the Cl⁻ 2p⁻¹ photoelectron peaks.