Franck detachment process

For the series of 4m-1-2 carbon rings (m = 2-4), the photoelectron spectra exhibit rather broad bands [6,36]. Since, in the anions, the occupation with an electron of the degenerated LUMO level may lead to the FOJT distortion to lower the molecular symmetry, the electron detachment process should accompany a deformation between the different symmetry structures leading to complex excitations of more than one vibrational mode. The anionic Cio is calculated to have C2V symmetry while 7)51, symmetry for the neutral, thereby C2V —> Fish transition from the anion to the neutral species gives rise to a large Franck-Condon shift consistent with the observed UPS spectra [38c]. 

A first working interpretation of the behavior of the trimer is this initially, the neutral is produced in a linear configuration by the vertical, Franck-Condon detachment process. Figure 5.5 summarizes neatly this hypothesis. The Franck-Condon overlap factor of the linear neutral with the equilateral... 

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