Photoionization of zwitterionic liquids

The electronic structures of three zwitterionic liquids (Zw-IL) have been studied using high-level ab initio method: equation-of-motion coupled-cluster (IP-EOM-CCSD) method. This method was found to match experimental UV photoelectron spectrum (UPS) of related N-methylimidazole better than Outer-valence Green’s Function (OVGF) method or Symmetry Adapted Cluster-Configuration Interaction (SAC-CI) method. Zw-IL gas phase photoelectron spectra have been simulated in the valence ionization regions based on the vertical ionization energies calculated. Valence ionizations have been attributed to specific molecular orbitals to specific functional groups The calculated electronic structures and valence ionization energies of Zw-ILs can be related to their polarizability which in turn influences the AC conductivity. AC conductivity is one of the principal properties of Zw-ILs which makes them very useful as electrolyte materials in lithium ion batteries or electric capacitors.