Consistent Assignment Of The Vibrations Of Monohalosubstituted Benzenes

When substituted benzenes become a focus of a spectroscopic study there are various well known vibrational labelling schemes present,\footnote{E. B. Wilson Jr., Phys. Rev., 45, 706 (1934)}$^{,}$\footnote{G .Varsanyi, Assignments of the Vibrational Spectra of Seven Hundred Benzene Derivatives,Wiley, New York, 1974, Vol. I and II} however it was shown in recent works the description of monohalobenzene vibrations in terms of benzene modes (ie. Wilson notation) is questionable in some cases.\footnote{I. Pugliesi, N. C. Tonge and M. C. R. Cockett, J. Chem. Phys., 129, 104303 (2008)}$^{,}$\footnote{A. M. Gardner and T. G. Wright, J. Chem. Phys., 135,114305 (2011)} A new scheme is presented which uses the motions of monofluorobenzene vibrations as a basis for labelling vibrational assignments of monosubstituted benzenes.$^{d}$ The scheme has been successfully applied to the ground and excited states of toluene and its deuterated-methyl group isotopologue.\footnote{A. M. Gardner, A. M. Green, V. M. Tame-Reyes, V. H. K. Wilton and T. G. Wright, 138, 134303 (2013)}$^{,}$\footnote{A. M. Gardner, A. M. Green, V. M. Tame-Reyes, K. L. Reid, J. A. Davies, V. H. K. Wilton and T. G. Wright, manuscript accepted} Here we present the application of the scheme to fluorobenzene and its fully deuterated analogue. One-colour resonance-enhanced multiphoton ionization (REMPI) spectroscopy was employed in order to characterise the fluorobenzene and fluorobenzene-$\textit{d}$$_{5}$ excited state