Assignment of the vibrations of the S1 state of monohalosubstituted benzenes:

69th International Symposium on Molecular SpectroscopyUniversity of Illinois at Urbana-Champaign

WI08/ P515

Anna Andrejeva, Joe P. Harris, William Tuttle and Timothy G. Wright

Introduction• Mi 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-h8 and toluene-d3 • Vibrational assignments are made for higher energy region of toluene-h8 and toluene-d3

• Lawrance group have utilised Mi nomenclature in their work

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 Mi

• Vibrations having the same atomic motion are given the same label

Figure 1. Calculated Duschinsky matrix elements for fluorobenzene S0 vs chlorobenzene S0.

What about…i) Deuteration? ii) Excitation?

Cl Cl

d5

Cl

S1 S0

C-Cl: S0 – 1.76 Å S1 – 1.72 ÅC-C: S0 – 1.39 Å S1 – 1.42 Å

35Chlorobenzene / 37Chlorobenzene

Assignments M30 M11 M29 M14 M19 M10 M9 M8

35ClBzExp. / (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)

37ClBzExp. / (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)

35Chlorobenzene / 35Chlorobenzene-d5

Assignments M30 M11 M29 M14 M19 M10 M9 M8

35ClBz-h5

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)

35ClBz-d5

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)

M9M8

79Bromobenzene/ 81Bromobenzene

• Harmonic vibrational frequencies are being calculated

79Bromobenzene / 79Bromobenzene-d5

• Equivalent M29 and M8 band shifts in 79bromobenzene-d5 are seen as in 35/37chlorobenzene-d5 spectra

Concluding remarks

•The same vibrational motions have the same Mi label for all monosubstituted benzene molecules regardless of the energy ordering or changes in molecular symmetry, allowing straightforward comparison between species

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