1. Assignment of the vibrations of the S 1 state of monohalosubstituted benzenes: 69 th International Symposium on Molecular Spectroscopy University of Illinois at Urbana-Champaign WI08/ P515 Anna Andrejeva, Joe P. Harris, William Tuttle and Timothy G. Wright

2. Introduction M i mode labelling (Gardner-Wright scheme) 1.A. M. Gardner and T. G. Wright, 135, 114305 (2011) 2.A. M. Gardner et al., J. Chem. Phys., 138, 134303 (2013) 3.A. M. Gardner et al., J. Chem. Phys., 140, 114308 (2014) 4.J. R. Gascooke and W. D. Lawarance, J. Chem. Phys., 138, 134302 (2013) — new nomenclature where ring- localised vibrations having the same atomic motion are given the same label, allowing these vibrations to be compared straightforwardly across different substituted benzenes Assignments of the vibrations of low energy region of toluene-h 8 and toluene-d 3 Vibrational assignments are made for higher energy region of toluene-h 8 and toluene-d 3 Lawrance group have utilised M i nomenclature in their work

3. Fluorobenzene vs Chlorobenzene Fluorobenzene vibrational modes serve as a model upon which benzene derivative vibrations are labelled. Each mode corresponding to a vibration is given the symbol M i Vibrations having the same atomic motion are given the same label Figure 1. Calculated Duschinsky matrix elements for fluorobenzene S 0 vs chlorobenzene S 0.

4. What about… i) Deuteration?ii) Excitation? S 1  S 0 C-Cl: S 0 – 1.76 ÅS 1 – 1.72 Å C-C: S 0 – 1.39 Å S 1 – 1.42 Å

5. 35 Chlorobenzene / 37 Chlorobenzene AssignmentsM 30 M 11 M 29 M 14 M 19 M 10 M9M9 M8M8 35 ClBz Exp. / (calc.) cm -1 288.6 (286.0) 379.4 (374.5) 523.2 (512.1)526.8 (459.4)673.6 (672.5) 935.2 (945.8) 968.4 (968.7) 37 ClBz Exp. / (calc. ) cm -1 286.4 (283.8) 375.4 (369.1) 523.2 (512.0)527.4 (459.4)673.8 (670.2)934.8 (954.8) 968.0 (968.7)

6. 35 Chlorobenzene / 35 Chlorobenzene-d 5 AssignmentsM 30 M 11 M 29 M 14 M 19 M 10 M9 M9 M8 M8 35 ClBz-h 5 Exp. / (calc.) cm -1 288.6 (286.0) 379.4 (374.5) 523.2 (512.1)526.8 (459.4)673.6 (672.5) 935.2 (945.8) 968.4 (968.7) 35 ClBz-d 5 Exp. / (calc. ) cm -1 273.4 (271.3) 371.2 (366.7) 502.4 (492.6)476.8 (391.2)651 (640.6) 783.2 (785.3) 925.8 (917.5) M9M9 M8M8

7. 79 Bromobenzene/ 81 Bromobenzene Harmonic vibrational frequencies are being calculated

8. 79 Bromobenzene / 79 Bromobenzene-d 5 Equivalent M 29 and M 8 band shifts in 79 bromobenzene-d 5 are seen as in 35/37 chlorobenzene-d 5 spectra

9. Concluding remarks The same vibrational motions have the same M i label for all monosubstituted benzene molecules regardless of the energy ordering or changes in molecular symmetry, allowing straightforward comparison between species

10. Acknowledgements Prof. Tim Wright Joe P. Harris William Tuttle for the processor time on their HPC I. Pugliesi and C. Schriever for developing program for DTA Project Studentship