Emission spectra of seven fluorobenzene cations

Author： Cossart-Magos Claudina Cossart Daniel Leach Sydney

ISSN： 1362-3028

Source： Molecular Physics, Vol.37, Iss.3, 1979-03, pp. : 793-830

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Abstract

The emission spectra of C 6 F 6 + , C 6 F 5 H + , the three C 6 F 4 H 2 + and two C 6 F 3 H 3 + (1, 2, 4 and 1, 3, 5) cations were obtained in the gas phase, in a special discharge tube. Symmetry and mode correlation of the fundamental frequencies of the parent neutral molecules enabled the isodynamic molecule method to be used for achieving vibrational analysis of the ion spectra. The vibronic structure in each emission spectrum is interpreted. Dynamic Jahn-Teller effects are shown to occur in the degenerate ground state of C 6 F 6 + and of 1, 3, 5-C 6 F 3 H 3 + , in particular irregular ground-state progressions in mode 6 are observed. Extensive Jahn-Teller calculations were made for 1, 3, 5-C 6 F 3 H 3 + ; frequencies and intensities in its progressions are in good agreement with the results of calculations based on the linear coupling model of Longuet-Higgins et al. , using a deperturbed frequency &ohgr; = 477–484 cm -1 and a dimensionless interaction parameter D = 0·13-0·10. A review of the vibrational data of photoelectron spectra and Rydberg far-ultra-violet absorption of C 6 F 6 and 1, 3, 5-C 6 F 3 H 3 shows that some reassignments are to be made in the light of the present work.