Double-Core-Hole States in Neon: Lifetime, Post-Collision Interaction, and Spectral Assignment

Using synchrotron radiation and high-resolution electron spectroscopy, we have directly observed and identified specific photoelectrons from K⁻²V states in neon corresponding to simultaneous 1s ionization and 1s→valence excitation. The natural lifetime broadening of the K⁻²V states and the relative intensities of different types of shakeup channels have been determined experimentally and compared to ab initio calculations. Moreover, the high-energy Auger spectrum resulting from the decay of Ne²⁺K⁻² and Ne⁺K⁻²V states as well as from participator Auger decay from Ne⁺K⁻¹L⁻¹V states, has been measured and assigned in detail utilizing the characteristic differences in lifetime broadenings of these core hole states. Furthermore, post collision interaction broadening of Auger peaks is clearly observed only in the hypersatellite spectrum from K⁻² states, due to the energy sharing between the two 1s photoelectrons which favors the emission of one slow and one fast electron.