Electronic excited state of protonated aromatic molecules: protonated   Fluorene
  The photo-fragmentation spectrum of protonated fluorene has been recorded in the visible spectral region, largely red shifted as compared to the first excited state absorption of neutral fluorene. The spectrum shows two different vibrational progressions, separated by 0.19 eV that are assigned to the absorption of two isomers. As in protonated linear PAHs, comparison with ab-initio calculations indicates that the red shift is due to the charge transfer character of the excited state. 
Ivan Alata (CLUPS), Michel Broquier (CLUPS, ISMO, PPM), Claude   Dedonder (CLUPS, ISMO, PPM), Christophe Jouvet (CLUPS, ISMO...
physics.atm-clus physics.chem-ph