[en] photoelectron spectroscopy ; 1,1-C2H2F2 ; synchrotron radiation ; ab initio calculations ; vibrational excitation ; electronic excited states ; autoionization ; conical intersections ; avoided crossings
[en] The threshold photoelectron spectrum (TPES) and the constant ion state (CIS) spectra of the individual ionic states of 1,1-C2H2F2 have been recorded using synchrotron radiation. The TPES has been measured between 9.5 eV and 28 eV photon energy. For comparison the HeI photoelectron spectrum (HeI-PES) has also been measured and analyzed in detail. Numerous vibrational structures, reported for the first time, observed in the ground state and the seven excited states of the cation are analyzed. Quantum chemical calculations have been performed and provided support to the assignments. The exceptional contribution of autoionization to the HeI PES could be emphasized. State selected CIS spectra highlighted the importance of the autoionizing contribution to the production of almost all ionized states of 1,1-C2H2F2 observed in this work. Several peculiarities of the vibrationally resolved CIS spectra are analyzed.
Molecular Dynamics Laboratory
Belgian Fonds de la Recherche Fondamentale Collective - FRFC, European Union by HPRI-1999CT-00028 and RII3 CT-2004-506008