1. William D. Tuttle, Adrian M. Gardner, Laura E. Whalley and
Vibration and vibration-torsion levels of the S1 and D0+ states of pFT and para-xylene below 1000 cm-1
William D. Tuttle, Adrian M. Gardner, Laura E. Whalley and
Timothy G. Wright
ISMS 2017, Vibrational structure/frequencies, FC June 23rd 2017

2. Importance of vibration and vibtor levels
Continuation of work on the lower wavenumber regions of pFT and para-xylene; discussed by Adrian (TD08, TD10) and Peter (TD09) on Tuesday .
Understanding how vibrational levels couple, and the influence of internal rotation levels on those couplings, is key to understanding how vibrational energy may be spread throughout a molecule.
para-xylene5,6
para-fluorotoluene3,4
Toluene1,2
1A. M. Gardner et al., J. Chem. Phys., 138, (2013). 2A. M. Gardner et al., J. Chem. Phys., 140, (2014).
3A. M. Gardner et al., J. Chem. Phys., 145, (2016). 4W. D. Tuttle et al., J. Chem. Phys., in press.
5A. M. Gardner et al., J. Chem. Phys., 146, (2017). 6W. D. Tuttle et al., J. Chem. Phys., 146, (2017).

3. Importance of vibration and vibtor levels
Resonance-enhanced multiphoton ionisation (REMPI) spectroscopy
Continuation of work on the lower wavenumber regions of pFT and para-xylene; discussed by Adrian on Tuesday
Understanding how vibrational levels couple, and the influence of internal rotation levels on those couplings, is key to understanding how vibrational energy may be spread throughout a molecule
para-xylene5,6
para-fluorotoluene3,4
Toluene1,2
Zero-electron kinetic energy (ZEKE) spectroscopy
1A. M. Gardner et al., J. Chem. Phys., 138, (2013). 2A. M. Gardner et al., J. Chem. Phys., 140, (2014).
3A. M. Gardner et al., J. Chem. Phys., 145, (2016). 4W. D. Tuttle et al., J. Chem. Phys., in press.
5A. M. Gardner et al., J. Chem. Phys., 146, (2017). 6W. D. Tuttle et al., J. Chem. Phys., 146, (2017).

4. REMPI Overview
7A. E. W. Knight and S. H. Kable, J. Chem. Phys., 89, 7139 (1988). 8Andrejeva et al., J. Molec. Spectrosc., 321, 28 (2016).

5. REMPI Overview
7A. E. W. Knight and S. H. Kable, J. Chem. Phys., 89, 7139 (1988). 8Andrejeva et al., J. Molec. Spectrosc., 321, 28 (2016).

6. 2D-ZEKE

7. 2D-ZEKE 91 Major contributing a1 and b2 zero-order states 144 292
111291
112/121141
182
142291/121m6(-)
111142

8. What about the analogous region of para-xylene?
182, 91 and 112 all observed in para-fluorotoluene and para-difluorobenzene
All totally symmetric
Possible interactions:
91…182
182…112

9. 4W. D. Tuttle et al., J. Chem. Phys., in press.

11. Back to pFT: weak bands and fundamentals
Note:
ZEKE spectra via weak REMPI features
many Δν=0 transitions, i.e. coincident levels
many vibtor levels
Able to get fundamentals for:
a1: D10
b1: D18, D17, D16, D15
a2: D13 (not shown)

12. Conclusions
Obtained firm assignments of S1 and D0+ levels of para-fluorotoluene and para-xylene utilising ZEKE spectroscopy and comparison of activity to para-difluorobenzene.
Investigated vibration-vibration and vibration-torsion couplings in para-fluorotoluene and para-xylene utilising (2D)-ZEKE spectroscopy.
From previous and current work, there are a remarkable number of overlapping levels in the S1 state which are unravelled with the used of ZEKE spectroscopy.
Obtained a large range of fundamental vibrational wavenumbers for pFT (all b1 and a2!) and para-xylene, which aid in assigning structure and unravelling couplings at higher internal energies, which is ongoing work.
Showed vibtor levels still important at higher internal energies.

13. Acknowledgements Thanks for your attention!
Professor Timothy G. Wright
Dr Adrian M. Gardner
Laura E. Whalley
Professor Peter Groner (University of Missouri)
Professor Warren Lawrance (Flinders University)
Dr Jason Gascooke (Flinders University)
EPSRC Grant: EP/L021366/1
University of Nottingham HPC facility
Thanks for your attention!