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, FC06 June 23rd 2017

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, 134303 (2013). 2A. M. Gardner et al., J. Chem. Phys., 140, 114308 (2014). 3A. M. Gardner et al., J. Chem. Phys., 145, 124307 (2016). 4W. D. Tuttle et al., J. Chem. Phys., in press. 5A. M. Gardner et al., J. Chem. Phys., 146, 124308 (2017). 6W. D. Tuttle et al., J. Chem. Phys., 146, 124309 (2017).

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, 134303 (2013). 2A. M. Gardner et al., J. Chem. Phys., 140, 114308 (2014). 3A. M. Gardner et al., J. Chem. Phys., 145, 124307 (2016). 4W. D. Tuttle et al., J. Chem. Phys., in press. 5A. M. Gardner et al., J. Chem. Phys., 146, 124308 (2017). 6W. D. Tuttle et al., J. Chem. Phys., 146, 124309 (2017).

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).

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).

2D-ZEKE

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

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

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

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)

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.

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!