PHOTODISSOCIATION SPECTROSCOPY OF GAS-PHASE FERROCENE CATION

The optical absorption spectrum of gas-phase ferrocene cation was measured by photodissociation (PD) spectroscopy between 570 nm and 643 nm. The PD process was loss of a cyclopentadienyl ring from the parent cation. Some structure was observed in the PD spectrum, with the highest PD being at 603 nm. The peak spacing did not correspond to a vibrational progression in the expected totally symmetric vibrational mode, and a possible assignment of the three apparent maxima involving electronic transitions from low-lying electronic states is proposed. Information on the dissociation threshold was sought by light intensity dependence measurements at 308 nm, 266 nm, and time-resolved PD measurements at 308 nm, 266 nm, and 240 nm. The PD at all of these wavelengths showed two-photon characteristics, indicating that the threshold for observable one-photon PD lies higher than about 5.4 eV.