DOUBLE PHOTOIONIZATION OF CO2, OCS, C2H2, CF4, AND C6H6 STUDIED BY THRESHOLD PHOTOELECTRONS COINCIDENCE (TPESCO) SPECTROSCOPY

Double photoionization of CO2, OCS, C2H2, CF4 and C6H6 molecules has b een studied in an electron-electron coincidence experiments, where nea rly zero kinetic energy (less-than-or-equal-to20 meV) electrons are de tected. This first application of TPEsCO spectroscopy to polyatomic mo lecules confirms the ability of this experimental technique to determi ne accurate double ionization potentials and locate excited electronic states. The spectrum of benzene reveals what appears to be the first observation of vibrational structure in a polyatomic dication.